It is quite hard to identify which coin is a scam or not. Most of airdrop coins now ended up being worthless, but it doesn't matter for me, since I haven't done a lot of job getting that free coin. If we got involved on an airdrop, we can also check their announcement thread if they have and see if their team are strong enough to become successful or their project has something different to offer that might stand up at the end. Sometimes reading about them may answer our doubt, but sometimes not at all because we still cannot say if the project will goes well. But don't throw your coins away, it would be a regret if something good happens. But it will not if you just  keep it.