I think i know where you''re headed with this whole thing. You have to understand that not everyone is going to be that honest and tell you exactly something along the lines..."Oh, i dont find you attractive enough to go out with you"...Therefore, yes, at CERTAIN times, they will tell you that they see you as just a friend to not hurt your feelings. Second, there are OTHER times when there is that bond between a male and female however it feels more of a brother/sister relationship so it would be very awkward to start something, not to mention you're at a risk of losing a great friend.
Either way, if you're getting into those problems, it's mostly because you're not establishing yourself as someone who wants a g/f earlier on. This way, you know what you want, you either get it or you don't, and that way you won't have to worry about being stuck in the "friend zone".
-to be nobody but yourself in a world which is doing its best, night and day, to make you everybody else means to fight the hardest battle which any human being can fight; and never stop fighting.- e.e.cummings