^That sounds like the 'get you coming AND going' argument. If somebody doesn't like the sound of a trek movie and doesn't want to see it, he is told his opinion doesn't count because he didn't see it, and then if he does eventually see it, his opinion doesn't count because he was prejudiced against it to start with. You gotta pick your parameters, you can't have it both ways.
I think it's one thing to think something may not be of interest to you then seeing it later on and not changing your mind. It's another to bang on how much you hate a movie for six months then go "oh god, I hated it!"
I'm reminded of a poster here who graded the film an 'F' weeks before it came out here in the States, slammed the movie over and over and over then saw it recently and hated it.
Do I believe that person really hated the film as much as they said they did? I don't know? That person expended so much time and energy hating on a film they hadn't seen that I'm not sure they would have had the courage to admit they were wrong.
So I usually don't believe folks who act in that manner.