A lot of the reviews on the cheap ones are fakes, about two years ago I got emailed shot loads from amazon seller was offering me free products in exchange for reviews.
People leave good reviews for these items even if they are shit and a lot leave five star reviews without even using the item and list it on eBay.
I know this because a few years ago I got offered free stuff myself. Some stuff was good, some absolute tat but you'd see hundreds of positive ones all from other people who got the item free. I stopped doing the reviews because I didn't want to lumped in with the bullshitting fake ones.
Amazon is supposed to have put a stop to this but all that's happened is reviewers ni longer disclose they were given the item for free and it'll show "verified purchase" because the sellers now ask you to buy with your money and they give PayPal refund after leaving a five star review. I get emails every week offering me tat.
If you look at the reviews and you have a lot of people posting photos of the product in the packaging alongside a five star review they are likely fake reviews and I wouldn't touch with a barge pole.
I was sent a cheap Fitbit thing and it was shit. Seller said it was faulty and sent a second that didn't count, then a third, fourth and fifth claiming is been unlucky and hit faulty ones. Nope, it was shit product overinflated to looks better with people bullshitting in their reviews to get more free products.