honestly, half of the people i see out there selling the fakes say "Tamagotchi Toy" not a real Tamagotchi, they also don't even say anything about the company Bandai, and say "For lovers of Tamagotchi's and children who like these products" which, essentially means, that the tpy is for people that like Tama's, not for Tama Collectors and things like that.
THIS IS NOT TO SAY that there aren't really fakes out there, because there are, but the ones that I have seen have never really claimed directly to be from Bandai. IF, however, they have, then that means that they have broken Copyright, and can be sued/arrested.
Another thing that I've seen, not only here, is a lot of people complaining about fake Tama's that are really just Japanese Tamagotchi's, i.e. the packaging and colors are different, as well as the keyring is sometimes replaced with something like a clasp or a string of cute beads. If someone is asking politely if the Japanese Tama is a fake, that is fine, but what I have seen is people cursing and yelling that the Tama is a fake and is destroying their lives. it's a little bit ridiculous sometimes. This is not saying that everybody does this, I'm simply saying that there are some that I have seen that are overreacting incredibly.
As for it noe being obvious that a Tamagotchi is fake, there are some signs that make it completely obvious. Like, if you see a packaged Tama that looks real, but the Mametchi's little cap is light blue instead of dark blue, or something like that, a pink Violetchi, a yellowish Kuchipatchi, then this is most likely a fake. Generally, people try to not be able to get into trouble by changing something small and saying that the item isn't really a Mametchi, so you should have known, or something like that.
There are also some people that say that the item on eBay or wherever is a Tamagotchi Toy, but it's an egg shaped Gigapet, normally that's just something like the seller really just thinks its a Tama. Don't you remember the days where your parents called them "Tammygoochis" or "Tamawhatzits" some people really just don't know that the item is not a Tamagotchi and thus label the item wrong. Just message them about their mistake.
There are indeed many fakes out there, but most of them are making their own toys and not labeling them Bandai, and thus not really in trouble, and then Bandai cannot really do anything about it. Others can be making thier own toys that have nothing to do with Tama and are really just a keychain Virtual Pet, andd not a Tama. There are those out there, you know? Nano Pets, Gigapets, some even are just ones where you raise a dinosaur or a chicken or something. So, sometimes, just take a breath and calm down before screaming for the cops. Things happen.