As good as some airdrops are, so also many airdrops are nothing but waste of time and other resources. Imagine trying to do some works in getting a particular airdrop and at the end of the day when you get it, two years you're are still looking at it in your wallet without any hope of it listing on any exchange. In the other hands, some scammers create their own airdrops in order to obtain vital information about the participants, then defraud them. We need to exercise extra caution when we want to join any airdrop.