Its very difficult to determine if an ICO is a scam. Nowadays its hard to find a good and reliable ICO and the only way to avoid it is to really check and do some research on that specific ICO that youre investing on. And make sure that all youre details are secure.
you are right. even I have been hit several times by scams from several ICOs. well, sometimes I see an ICO with the concepts they offer, and if it's interesting, I find out the competition from that project. sometimes it really does. however, sometimes an unprofessional, irresponsible team starts to show their injustice and begins to disappear. well, sometimes an ICO can be valued by their team.