-Look out for the bounties and airdrops in the bounty and airdrop listing- website.
-Look for the response it gets on bitcointalk.
-Read the whitepaper of the ICOs properly and understand the tokenomics.
I prefer these to be some of the basics that we can do in order to stay aware of scam bounties and airdrops.
Well you can't really say whether the ICOs are scam or not, I have seen many bounties with long threads on BTT, but guess what they turn out to be scam in the end!1

Right but we can filter out more than 50% of those projects which by going through their social medias. If the devs and admins are available and online plus the idea and the team is good, then they can be trusted. Always look out for all the socila medias before doing any airdrop or bounty. It'll save a lot of efforts and time.