The problem is, nobody wants to be the evil guy that rips another guy's dream to shreds. That's why, when asked directly, people will always say that your thing is a cool idea, looks great, etc.

It is said that entrepreneurs need to develop hard skin. I propose that this hard skin should extend to ignoring this kind of vapid feedback. Because with our typical starry-eyed optimism (/ denial), we often see these as validation, when they're really not.

One thing I've learned is also to always listen to the 'assholes', you know the guys who tell you that your thing sucks, looks like shit and so on. They are often valuable resources because at least they are being honest - if you engage them and try to get them to flesh out their criticism. Some of the best feedback I have ever gotten was this way.