The best way to away from this scam airdrops, ICO's or any project. do a profound research about the project you are to join in. and don't easily fall from what you see in the internet.
in-depth research will certainly be done by everyone before they join a project. sometimes a scam problem or not we can't know it. I also took part in the final bounty from the campaign to buy participants but until now I have never registered in the trade market. So to make a study regarding a scam project or not is very difficult.