If I may, I'd like to purport that the perception of watching, or even enjoying the series as being "gay" (not literally homosexual) is slightly incorrect. Instead, I believe it's the manner in which it is lauded, coveted and defended that brings about the accusations, insults and "faggot" being thrown about more than at a PRIDE parade. The enjoyment of something feminine, in this case Friendship is Magic isn't the attack on/lack of masculinity but rather the beta-masculinity that, unfortunately, seems all too common.
(For the sake of brevity, I'd like to sate that when I use the term masculinity it is done so in the sense of separating boyhood from manhood and not bare-chested testosterone poisoning, no matter how awesome.)
An inability to accept criticism. An unwillingness to accept that others don't accept our subjective taste in toons. A woeful lack in number of those willing to step up to the plate in a mature manner and be okay with leaving their interest as an interest and not as the driving force of their personality. I see the series as a children's fair in a park, open for all to enjoy, but a great many of us are all too willing to claim all of the festivities as their own in spite of those with little recourse.
Assaults on another's sexuality, mostly though "gay" and "faggot" have long evolved from a direct slur to homosexual men. The roots are still there, obviously, but those that resort to this ammunition aren't insisting that you're gay for watching the show or being part of the fandom.
They're insulting one's lack of masculinity. That the insulted is less of a man. Unfortunately, given the manner as to how a vocal portion of our fandom acts, I cannot with all honesty intact, say that questioning the overall masculinity is not unwarranted sometimes.