There is no quick way to know a good airdrop until the team behind it is unveiled. I have seen so many airdrops that I know would never succeed, maybe ending up scamming their victims with poor allocation after so many promises. We should not expect too much from airdrop because many of these project devs are not considerate after so many promises. I have participated in so many airdrop and their are some that are impressive and their are some that give out poor allocation making investors to panic after taking their time to mine consecutively without anything tangible.
it is necessary to consider the airdrop you choose, because not all airdrops get commensurate payment, but in terms of people's different thoughts, even though they get auncommensurate reward,they still visit it, for the reason of having a lot of free time to spend it.
The expectations shouldn't be too high.
There are many airdrops out there, but only a small portion of them would deliver.
I would say not more than 10 of them.