Sadly it took me a few times to get burned and scammed to realize this but I am quite picky now when it comes to these things. I think I did really well on one of them so I kind of broke even which was very lucky of me but other than that I despise ICOs. Why not get the token or coin cheaper than ICO price on exchange in a few weeks? That way you got better price and no risk it seems like a win win to me.
Other thing you have to consider with ICOs is how long you have to wait before the coin is listed on the exchange. It is a lot larger risk if you have to wait a long time before receiving the money back, e.g. Polkadot's ICO. Locking up your eth for almost two years.