Majority of the airdrops seems promising and reliable, some time it is even those one that you didn't find interest in that end up more rewarding, making personal research doesn't even guarantee that an airdrops is going to be rather it gives a guide. However, balancing or lowering our expectations from airdrops has always been my best advice to anyone because I know how disappointed it can be when you overly hope on something and get even less or completely nothing out of it. Do as little as you can and expect less so that When it becomes big it ends up being a surprise which I prefer most.
The "trick" most have is that they do not want your money, so that makes them look more trusting, since if they are not taking your money, what harm they could have? But the reality is, they are using thousands of people as a workforce for free, they are not paying a single penny, they are just giving the token they created for free, and in exchange, they are getting paid bunch of money from funding by others, who invested because of all the workforce doing marketing for them.
The project creators themselves didn't do anything, they just created fake money, and airdrop people convinced investors to put their money into this project, so their airdrop money would be worth something. Hence, I never liked airdrops to begin with.