yes there are a lot of scam bounties out there and they can be found mostly in altcoin > bouty section. ive been also a victim of it several time when i was a newbie on this forum because as a a newbie i can only participate on a bounty/ico campaign and not on a  signature campaign that pays in bitcoin weekly however i still receive some altcoins on some bounty that ive joined but the problem is their coins are still pretty cheap and likely to become worthless as the time goes because the devs are not active anymore on them to develop it and finished their roadmap.