I think common sense comes into play with this... if you can genuinely get excited about a project and see yourself wanting to use it, that's always a good start! Then thoroughly look into the team's credibility, skills and competency and that it is a legitimate enterprise. Obviously partnerships with already existing, respected and credible companies, and/or investors can give you some confidence also.
You should clearly be able to see that it can and will be used for its utility or value in the future, and that others are getting behind it also. Just keep in mind that even the most professional looking websites, team and hype from supposed communities can be false (these things can be hacked and bought)...so just be sure to look closely and don't take anything at face value.
But I agree, there are still some good ICOs out there for sure! But with the direction the industry is headed their position with regards to legality and regulatory compliance ought to be clear as day. If not, their scalability and future will be short-lived, or inevitably shut down.