More and more airdrop is a lie, I do not recommend participation in airdrop, because there are at most a few 100 airdrop quality, so I think it should not be a waste of time.
Almost all airdrop are trash, you can simply go to the first page on their Announcement thread, there are so simple and only talk about airdrops. All these thing are trash and when the coins accepted on etherdelta, the dev will dump all the coins. Only 1-2 project airdrops will become succes others are not.
Most of airdrops are complete trash I totally agree, but not all of them. I've been participating in almost 200 airdrops, and I sold about 10 tokens for a pretty good price, in total for almost 3 ETH. And if you consider I haven't put any money in those airdrops, that is an excellent profit.
I agree most are trash or scammy. I generally work on the rule if I don't have to give my private key, email or donate then I will give my time and have a look at the project. Maybe 5% of airdrops I see I sign up to and most of those have been profitable. Just got to pick the right projects.
Bounties are still a better choice but once again you need to do research on the project to pick the winners.