There are so many ICOs due to the fact that there are close to no barriers to create one. NEO ICOs have a barrier, and there are way less scams there. Also, some form of regulation would be needed.
It is not so easy to determine which ones are scams. But the question, how can you determine is an ICO is scam, has been asked around a hundred times in this forum already, and I'm going to sum it up shortly.
0. Look at the project. Is it credible, and based on a good idea? If not, it will make it really hard to actually make profits on your investment.
1. go to icobench/icodrops/etc. and select a project with moderately good ratings. Read the critics, and focus on that, and you can learn what are the weak points of the projects.
2. Look at the team. Are they competent, how much experience they have, and what connections/partnerships do they, or the project have. If they have partnerships with famous companies, that is a highly positive thing.
3. Read the whitepaper. You might already know what they are doing, so focus on how the whitepaper is written. How professional is it, what do they emphasize, how they phrase sentences. I have read and translated plenty of whitepapers, and boy you can extract so much "hidden" information by simply reading the whitepaper thoroughly.
4. Look for further red flags. If you haven't seen any already, that is a good sign. If you did, consider your options, weigh what is against is, and then decide.
I hope I helped!