I think many people lump scams in with ICOs that intend to have a viable business, but have a small chance of success.  Yes, there are many scam ICOs, but there are also many that just have very little chance of success because of a weak team, competition/market factors, or a bad business model in general.  As many others have said, most startups do fail, and you should not expect anything different from ICOs.  

Check that the people behind the project have a good reputation and experience, the resources (financial, connections, etc.) behind them, and understand the business model and market well before making an investment.  Follow these things regularly to stay up to date, just as you should any other kind of investment.

Could you explain what you mean by this? How is the Nitro team not clear about the existence of the project?  There's been a lot of publicity with this one, including an article on Forbes, an interview on CNBC, announcements from the publicly traded company iCandy, etc.

Most IPOs are either a scam or have very little chance of success.. with that said, there are some really great projects when you look below the surface.  As always, know what you're investing in.. understanding the technology as much as you can, competitors, the team, the market.  Same way you'd evaluate a "traditional" investment.