Maybe it depends in the success of the project I will not call it scam if you didn't invest any amount of money if just joined bounties and airdrops
basically a scam is when a project has achieved success in sales but does not continue to develop and is left behind by its team and community.
if we are only incorporated in the bounty and airdrop will also be able to feel that it is a scam or not, because without these two things I think a project will also not be able to develop bigger.