I think Shortpacked pretty much says all there needs to be said about being a fan of something. Being passionate about something is great, but it should never blind you in your day to day to actions/behavior. Chance are what your passionate about was meant to being joy to the world. If it was meant to harm, then chance are Fans never want to see it see used for evil/immoral/dark reasons because it shames them and their passion. The military is great example something that was meant to harm, but ends up being a force of good if used properly and carefully. No solider views themselves as evil, and must take a leap of faith when they're called in to serve, that what they're doing will bring some good to the world someday, even if they don't live to see the pay off.
That said, Star Wars Fans, and Trekkies are not the worst fanboys/Fangirls out there, politicians are. Just because they wear suits and command power doesn't make their passion any less dangerous. When we disagree, our egos get bruised, but when they do, lives get ruined either through their inactivity or activity. Not to mention their popularity contests can really degrade themselves, their supporters, and the country they love.
Shit, now you all know how weird I am.
Edit: It just occurred to me: The worst action preformed any Transfans has ever done to another human being was the Bomb/death threats to Bob Skir.