You just gotta put more time to research the airdrop honestly.

Plenty of good airdrop happened recently such as HUMA, SOPHON and so on, but yeah there are also many projects that exist just to grift on the community and milking their users.
So you really need to do a thorough research otherwise you're gonna waste your time and money.

But doing research isn't as easy as it sounded, there's always other factor that can turn a supposedly good project into a bad one.