I was a Star Trek fan before I really got in to writing or talking with other kids who were into science fiction - Trek premiered on NBC when I was in junior high school, and was cancelled before I got to high school.
At high school there was a science fiction club. Surprisingly, the kids who ran it - seniors, of course, two years ahead of me and my friends (which seemed a tremendous gulf of experience, a life time, really) - were dismissive of Star Trek. They'd read a lot more prose sf than I had; the sf literary lions of the day were still the old pre-"New Wave" guard, people like Heinlein and Asimov and some others who are not really well remembered at all now (Clement, Anderson, Pohl). One senior who was determined to be a writer talked about Brunner and Ellison a lo.
Star Trek, as it turned out and according to the Big Kids, was made of stolen parts and, almost as important, didn't handle any of them very well. The failings of logic in the show and the scientific errors (as close to cardinal sins as one could get amongst ser-con fanboys of the day) were legion. It was badly written, etc., etc.
And, of course, Star Trek was also a big failure that gone off the air a year or two before and there was really no reason we should still be paying any attention to it, anyway.
Oh, and one guy* insisted that the whole series was completely stolen from a much better science fiction movie of some years before, Forbidden Planet. That meant nothing to me at the time. I remembered it years later when I first saw the movie on TV in a college dorm. And, yeah, it turned out that Trek pretty much was.
Anyway, I was reminded of all this last evening while paging through an old book about Trek written by David Gerrold. The first Star Trek convention was apparently put together by some New York science fiction fans at a hotel well-known there for hosting sf conventions. According to Gerrold, they were tired of being mocked and shooed off at gatherings like Lunacon for seeming to prefer the dumb TV show to the clearly superior and more varied material that the majority were into.**
That was a long time ago, and I don't guess any of it matters any more.
*There was one young woman in the club. I would learn later that this would be almost stereotypically true of science fiction groups I would find throughout my college years - except for Star Trek clubs. This may explain my throwing myself so completely into Trek fandom during those years.
**According to contemporary accounts, the first couple of episodes of Star Trek were shown at a Worldcon in 1966 and the science fiction fans were pretty excited about it. Well, at that time it was a couple of cool short films without a few thousand fanatics wrapped around it. Later sf fans probably really disliked Trekkies a lot more than they disliked Star Trek.