23 Products You Should Never Buy on Amazon

1 | Batteries

Batteries aren't a great buy on Amazon. Even on sale, the AA Energizer batteries being sold on the site come out to $0.67 per battery, and you can buy Costco's Kirkland brand at any given time for just $0.35 per battery. Though the Amazon Basics AA batteriesseem like a better deal at $0.26 per battery—when you buy 48 of them—the Costco ones get better reviews. When Consumer Reports teamed up with CBS12 to determine the best AA battery, they deemed the Kirkland Signature Alkaline the "best buy."

2 | Certain Smart Devices

The only smart devices you should ever buy on Amazon are, well, Amazon's. Otherwise, you can pretty much guarantee that you'll pay the manufacturer suggested retail price, or MSRP—if not more.

"Amazon sells a couple of Google devices, but they usually go at list price," Tom's Guide deals editor Louis Ramirez said to CNBC Make It. "If you want the Google Home Mini, or any of the Google smart home devices, your best bet is to go to Walmart."

3 | Groceries

Despite the fact that Amazon now owns Whole Foods, that doesn't mean it's the most cost-friendly place to buy your groceries. Take Smucker's Strawberry Preserves, for instance. On Amazon, a pack of six 12-ounce jars comes out to about $15, or $2.49 per jar. At almost every grocery store, though, you can buy a single 12 oz. jar of the fruity spread for $2, so Amazon's bulk "deal" is actually a 24.5-percent markup.

And even if you use Prime Pantry to fill your kitchen, you have to use it wisely to get your money's worth. Unless your cart is worth $35 or more, Prime members have to pay a flat shipping fee of $5.99 on top of what they're paying for their products. Sometimes it makes more sense to just go to the grocery store.

4 | Mattresses

While it might be tempting to have a mattress delivered directly to your door with a single click, Amazon isn't the best place to buy one. Certain web-only brands' generous return policies aren't as easy to take advantage of when purchased through the marketplace.

For instance, while Casper offers a 100-night trial on all of their mattresses, some customers report that the company's return policy isn't always honored by Amazon. Similar sentiments are seen in the reviews for the Nectar queen mattress, which is supposed to come with a 180-night trial period. "There was a huge back and forth between Amazon and Nectar on who to return it to (with neither wanting to take responsibility)," one customer wrote about their bad experience.

5 | KitchenAid Mixers

Don't be fooled by the sale prices that Amazon advertises for KitchenAid mixers. At best, Amazon's prices are only as good as other retailers', and at worst, they can't compare to the deep discounts that other stores offer during major sales like Black Friday.

At the time this article was published, a KitchenAid Artisan 5-Quart Stand Mixer with a retail value of $430 is on sale for $300 on Amazon. Meanwhile, a similar KitchenAid Artisan 5-Quart Stand Mixer with a retail value of $500 is on sale at Bed Bath & Beyond starting at just $230—and you can use a coupon to get an even deeper discount. Amazon's KitchenAid prices are average, if that.

6 | Collectibles

When you're shopping for certain collectibles on Amazon like rare coins or hard-to-find stamps, it's often the case that the seller isn't actually Amazon, but a third-party seller using the platform to peddle their goods. And, not unlike eBay, it's fairly simple to become a seller on Amazon.

As a consumer, what this means is that even on the biggest retail site in the world, you can't be certain that what you're buying is authentic. It's usually impossible to meet up with a seller in person to see an item before making a purchase, and so you can't verify with 100 percent certainty the authenticity of a rare coin or collectible Beanie Baby before sending over your money. And, while the Federal Trade Commission advises you to "ask if the item can be purchased and shipped to you on an 'approval' basis," this isn't a feasible option in most cases.

7 | Beauty Products

The sale of counterfeit cosmetics and beauty products is actually a big issue for Amazon. In a 2018 report, the Government Accountability Office determined that beauty and makeup products purchased from third-party sellers on the site were often not just fake, but also dangerous.

Of course, not every seller on the site is a fraud, but seeing as counterfeit products have been known to contain toxic chemicals, we'd advise anyone to play it safe and simply buy makeup from a verified retailer like Sephora or Ulta. As Sara Skirboll, fashion and trends editor at RetailMeNot, notes, "nothing is stopping third-party vendors from selling counterfeit products."

8 | Jewelry

If you're going to invest in a piece of fine jewelry, then you should do it right. "You are better off going to a brick-and-mortar store because you can see the product," Skirboll says. "On Amazon, there is no way to double-check that what you are paying for is what you are getting."

Further, as Kristen Dowling, a cataloguer at Philips Auction House, explained to Gizmodo, e-retailers like Amazon use marketing techniques to lure buyers into investing their money in products that are of a "low quality" and that aren't actually bargains. It always pays to visit a jeweler who can explain what you're paying for.

9 | Car Parts

If for some reason you feel so inclined to turn to Amazon for specific branded car parts, think again. In 2017, the e-retailer was sued by the parent company of Mercedes-Benz for selling counterfeit car parts, with the company noting that "Amazon refuses to take reasonable steps to police intellectual property infringement." Yikes.

10 | Designer Clothes

Think twice about buying anything designer on Amazon. According to the Harvard Business Review, fake luxury goods account for up to 70 percent of the $4.5 trillion spent on counterfeit items every year, and approximately 40 percent of all fake luxury sales happen online.

And even if you can confirm that an item on Amazon is authentic, do a thorough search of the internet to make sure that you're getting the best bang for your buck. Though Amazon's selection of name brand clothing is plentiful, Skirboll says that "you can usually get a better deal from department store sales. If you see a designer clothing item that you want from Amazon, do some research before buying it." The same Rebecca Taylor tweed jacket, for instance, goes for up to $476 on Amazon and $233 at Last Call by Neiman Marcus.

11 | Designer Bags

Designer bags are expensive enough, so the last thing you want is to pay more for a Michael Kors or Missoni than is absolutely necessary. However, there is a distinct possibility you will should you choose to buy one through the e-retailer. Both third-party retailers and sellers on the site are known to list their high-end handbags at inflated prices that, when compared to the general market, may not be worth it. At the time of publishing, for example, the same Coach Coated Canvas Chaise Crossbody is selling for $250 on Amazon and $188 at Dillard's.

12 | K-Cup Pods

K-Cups aren't cheap anywhere, but they can be especially expensive on Amazon. On the site, for instance, a 12-count of The Original Donut Shop Decaf K-Cup Pods are sold for $11, or $0.91 per pod, whereas at Target you can get the same pods in a 18-count box for $14.50, or $0.80 per K-Cup.

13 | Art Supplies

Do yourself a favor and go to Michael's or Hobby Lobby instead of Amazon for all of your arts and crafts essentials. Not only do the two specialty stores offer many coupons, but their prices pre-coupon are also usually better than those offered by Amazon. Even something as simple as a pack of eight Crayola crayons is just $1 at Michael's versus the $2.50 price tag it carries on Amazon.

14 | School Supplies

Anything your child needs for school can be found at better prices at Staples. And during back-to-school season, you can score great deals on school supplies at big-box retailers like Target and Walmart, as the Krazy Coupon Lady points out. According to Consumer Reports, brick-and-mortar stores work to stay competitive in the back-to-school retail landscape by offering discounts—plus you save on shipping costs.

15 | Add-on Items

Amazon's add-on items are quite deceiving. Sure, those Paper Mate pencils and tubes of Vaseline might look like a good deal, but there's usually a catch. For example, in order to buy them, you have to spend at least $25. If you already have at least $25 worth of goods in your cart, then go ahead and add a few add-ons to your cart; otherwise, just pick up some Vaseline during your next trip to the drugstore.

16 | Gift Cards

When you need to buy a gift card, either go to Costco or buy online via Cardpool. At Costco, gift cards for movie tickets, massages, and more are always on sale, and at Cardpool you can buy people's unused and unwanted gift cards for up to 35 percent off.

17 | Ikea Products

Sure, buying Ikea sofas and side tables via Amazon might save you the hassle of trying to navigate the stressful labyrinth that is an Ikea store on a Saturday afternoon. And that free shipping Amazon offers might look like a bargain, but anything from the Swedish retailer that you buy on the site is going to have a significant markup, discount website Brad's Deals points out. The same children's table/chair set, for instance, goes for $55 on Amazon and $30 on Ikea's website.

18 | Costco Products

According to a 2016 study by analytics firm 1010data, covered by Business Insider, the No. 1 seller of Costco-brand Kirkland products online isn't Costco—it's Amazon. However, that isn't to say that you should rely on the online retailer for your favorite Kirkland products. Per a 2019 analysis from Quartz, many items "appear to have a mark-up over their prices on Costco's own website."

19 | Kids' Shoes

While Amazon is great for buying discount diapers and toys, it doesn't have as many spectacular sales to offer on kids' shoes. For instance, one of the best-selling shoes on the site—the Adidas Originals Kids' Swift Running Shoe—varies in price from $24 to $142, while at Dick's Sporting Goods you can score the same shoe in any size for $55.

20 | Musical Instruments

Before you invest in a musical instrument, it's important that you test it out and really get a feel for how it sits on your body. And if you're a novice, then you'll also want to speak with a sales associate about which model is right for you before making a final decision. However, since Amazon is an online shop, neither of these things is possible.

21 | Used Software

You shouldn't run into any problems when you buy software on Amazon that's sold by a verified retailer like Intuit. You might find yourself with a faulty product, however, should you choose to purchase opened software from a third-party seller just to save a few bucks. As software site ProDesignTools explains, it's perfectly plausible for someone to try to pass off their Adobe software that's been rendered useless as a brand-new product.

22 | Weight Loss Products

Be careful about buying anything branded as a "weight loss supplement" on Amazon. In February 2019, the Federal Trade Commission (FTC) announced their first case against the internet giant after it came out that Cure Encapsulations, Inc. was paying a third party to "write and post fake reviews" for its garcinia cambogia supplement. Though the product was labeled as a weight loss supplement, the FTC notes that these claims were "false and unsubstantiated." To make matters worse, the supplement is known to cause liver failure.

23 | Edible Powders

You shouldn't buy a powdered product on Amazon—or through any online retailer—unless you are 100 percent certain that it's new and sealed. Things like powder baby formula and protein powder can easily become spoiled once they're opened, and especially after the 2018 formula-tampering scandal at CVS, it's always best to err on the side of caution (and inspect a packaging's integrity firsthand) when it comes to products that you or your children will be ingesting.