I would not trust such projects in which the development team anonymously. Developers and the roadmap are the main things that the investor needs to pay attention to before participating in the ICO. If the team is hiding their names it is necessary to ask the question - why do they do it?
Indeed, such projects are really unreliable but we can not say they are a scam project because, as your question, I think they have a reason to do so, and of course, they can also become successful projects if they have good ideas and plans. However, this rate is probably very low when many people do not believe in projects without clear information, and that makes these projects impossible to get enough capital to start the project, so, I think whatever the reason, the projects should also provide enough information to get the trust from the investor.