As unclingy as I am, I have to say that I'm not a fan of apathy either. You are either interested in someone or you aren't. If you aren't, then you should leave them alone, because that's how people are needlessly hurt. Seems a bit on the selfish side to me.
If I am truly interested in someone and a friendship grows into a relationship, I have no issue with letting a guy know very clearly how I feel, but I have no interest in pursuing a relationship with anyone unless I know the feeling is mutual. That takes some time and honesty.