it depends on many things, the developer and his history, the project itself and many other factors that help you make a decision but in general ICOs are bad and scam. they end up releasing a shit code and end up being one more shitcoin in the market.
that is why for me, the most important thing is the time after the ICO and if they can survive and get big so that i can earn more BTC from dumping it on top or not.
I invested in Ethereum as I see was nice team and nice visions. Much of today is shit. I see copy projects. I see projects with no codes. I see stupids peoples putting money in even stupider peoples hand.