In the past, many airdrops were legit and paid, but now it's probably only 1 in 100, of course, don't ever hope that we can get something wort it from airdrop now adays.
You don't really need to pay attention to airdrops with criteria as you mentioned, because in the past most legit airdrops also didn't ask participants to send eth on the grounds of fees, if you want to join an airdrop then just join airdrop with a simple task.