Previously, not many ICO are scams but now it's too much. For my own opinion, there are other ICOs that are complete paper works and very good in platforms but why it goes with the scam. Actually, it's very difficult to choose a trusted ICO so the best is to search for ICO spreadsheets that can tell you which ICO are scams and which is true. We must search first the team and their management background.
Research and risks is all you can do. We can't know if they are legitimate or not but I think the more people joining bounties in ICOs the more harder it is for the leaders to take the risk of scamming those people. I try as much as possible go with many ICOs that I think are good and start bookmarking those ICOs and if I have the ability, I support those ICOs that I think are great projects.
Just make a thorough research. Learn their objectives, find if they can be a step forward to new paths. Check their whitepapers. And finally decide if you want to support them or not.
ICO market became a high risk place for invesment when this market seems just for speculation. FOMO is the key to make the value of ICO token can reach high value. Because there are not much project have high x times value without FOMO. UTK, CS, INS, TRX, etc. many ICO had high price but current price are lower than the past a lot.