Search Results: what is first base in dating

Just been wondering about this, I only recently started dating again after a "break", and gone out on dates with a few girls in which, we generally got along well, had good conversation, then after the date, I'll text her and thank her for the good time, etc., then... (usually after a period where she ignores me), she texts back something along the lines of "You seem nice but I don't think we could be anything more than friends".

I'm just perplexed by this because how can a person truly judge whether a potential partner is right for them in a half hours' time at a coffee shop? Obviously people have their guard up on a first date and don't go too deep into who they truly are, nor can the other person judge this. Now, aside from the whole 'looks' thing (where the date sees you and finds they're not attracted to you; which is the only thing that makes sense if make that judgement based on one date), is it truly a good decision to judge your date during the first time you meet them in regards to whether they are right for you or not? Maybe if the date would give you a chance really get to know you after breaking the ice, they'd be able to more accurate judge if you are right for them. Why does this "quick judging" occur, you think? (besides the appearance thing)