You right, At this time legit airdrops number very rear.it's hard to findout.I think It's just time waste.Only 1-10% airdrops will give you coins and 5% are trade on cryptomarket.So before participating any this type off free airdrops or bounty everyone should check their roadmap,project quality,future goal.
But I have a chance that it will end in fraud, because how long you participate in the gift is likely to not get rewarded in the campaign, I think it depends on how you choose good to be more secure.