I've been doing airdrops quite actively since late last year when I started to really get involved in crypto.

I have to say that many are simply fake. Many twitter airdrops for instance are just fake accounts linked to fake websites (if that) and just want to accumulate followers so they can spam their referral links or get you to join their airdrop telegram group so they can spam their airdrop referral links there.

Sometimes it helps to check with the official coin account (on Twitter) or on their actual website to see if they are actually doing an airdrop or if its just a fake. The official coin account will usually put out a warning if there is a fake airdrop form circulating.