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.
Not all of them at all. I have joined some few of them which I solidly checked to be sure they really are a viable project and they are doing well now. Their prices have surged over the months, and I am sure they still will.
One thing is that, this is a community where anything goes and in most of these airdrops, majority of them are just there to gather crypto users information, so it is one thing to be careful so you do not start getting spam mails.
On the other hand, it is funny how most people rely on airdrops and thinking just because it is free, they really have nothing to lose. Some airdrops may have been relevant so far and doing good in the market, but most of them is just shitty. Nevertheless, there is no point clogging up once Ethereum wallet with some tokens that are not going to be worth it at the end of the day.