All Internet polls are self-selected, of course. That is indeed a limitation in how seriously such things should be taken.
That said, the difference between polls on a site and postings should be pretty obvious:
1) Negative voices are generally over-represented in posting. People are always more likely to voice complaints than express satisfaction;
2) The number of people who participate in polls tends to be much greater - hundreds rather than dozens - and therefore probably less skewed in one direction or another. Self-selected or no, one represents a much larger sample than the other.
The percentages come up amazingly consistently here, no matter what the precise phrasing or topic regarding the movie is: somewhere between eight and twelve percent negative toward any aspect of the movie (overall negativity is usually less than ten percent, while complaints about something like the appearence of the ship are more likely to edge higher). And this is on a site dedicated to
Star Trek and frequented by people who are almost by definition - self-selected, as you say - hardcore Trek fans. Beyond the hardcore, negativity toward this film is almost non-existent.
Pretty remarkable, considering the spotty recent history of the Franchise. This movie has already won over a greater percentage of the fan base than TNG was able to for its first couple of years.
