This is the worst problem on Amazon and it plagues many of the products I buy frequently. Particularly in the rather open world of 3D printers, it's difficult to discern the brand name from the clones (E3D v6 Extruder?). But it's awful for generic "parts" like bearings, where the quality parts can't even be sold on Amazon by third-parties because the fifteen pages of generics that cost 95% less make the likelihood of selling the higher-end one very low.

I guess the problem with the "everything store" is that you can't possibly get your arms around "everything" to make the purchasing experience consistent. As Amazon has moved to become "more like eBay", the quality of product listings has suffered immensely. The information needed to make an informed decision on a large chunk of their products is just missing and the wild-west of seller provided products leads to knock-offs and clone products that are difficult to discern quality versus junk. On many of these products, user reviews (if there are any) don't help because they require more than a hobbyist/amateur to provide a useful review. The usual defense is "returns are easy", but because of Prime, I use Amazon as a first choice when something breaks down. I need that part today, but there's no retail store that sells it, so tomorrow will do. If I could wait a few days, I'd use a trusted supplier who carries only the higher quality.

My most recent horrible experience with this was looking for 608 bearings. 608s are the same bearings used in inline skates[0]. Searching for them, however, requires you to use a variety of terms since the inline skate bearings almost never indicate that they're 608s. The user reviews for the kind I need are worthless, as is the price (high-end bearings are often unsealed, but also overkill at sometimes upwards of $100 for a set of 16). 608s, thankfully, have a standard rating (ABEC) that many people know about (but few really understand how limited this rating is). ABEC ratings indicate the tolerances of the bearings, not the resistance, but it tends to equate that higher ABEC bearings have less resistance. That is, until you search for them on Amazon. The first time I purchased bearings, I went to the Industrial/Scientific category and grabbed a set of four ABEC9s that I supremely over-paid for. They rattled and vibrated when spinning ... these were not ABEC9 bearings despite the italicized labeling on the rim. I returned them and replaced them with a set of eight ABEC9 inline skate bearings that were priced at $3.00 shipped (I've not seen a price even close to that since)! These had a mess of reviews that had the pattern of "They spun fine when I installed them but then ceased up after a few uses", indicating that they were almost certainly not sealed bearings[1]. After testing the ones I received, I promptly purchased 15 more sets of 8 in hopes I'd never have to hunt down 608s again.

[0] I learned that the inline skate versions are a little easier to discern quality from since the reviewer can tell pretty quickly. Bad bearings ruin the experience very quickly.

[1] I usually avoid inline skate bearings. You can usually trust the reviews for bearings that are very well sealed. You can't trust any others (including ones that claim to be sealed but really aren't). Buyers of bearings for inline skates often don't know using unsealed bearings will last anywhere from minutes to hours of use on a city street with debris ripping through them. Using sealed bearings in 3D printers and similar devices is fine, but you need to make sure you buy very good bearings because adding lubrication is nearly impossible (taking them apart without launching parts everywhere or breaking some portion of the bearing is almost impossible).