The complaint about every single fandom ever. "The DRAMA!" Or "It's TOXIC!" :D

I think the main issue is that people don't understand this fandom or find it childish or creepy.

Many throws off that furries usually are very open when it comes to sexuality and kinky things or certain fetishes that are not respected by everybody or uncommon. For many sex is a more private topic and they don't like it when people are too outgoing with it. Not too mention homosexuality, a topic that many people also don't wanna have to deal with and the fandom has many homosexual members too.

I assume many people think this fandom is where the "outcasts" of society end, who have nobody else. People who need to be ashamed for their likes, needs and interests. Of course that is absolutely not true. It's just that this fandom is more welcoming to people that are just a bit different or have unusual tastes, emotional problems or suffered in their lives and look for people which respect them how they are. Something other parts of society can't offer, because they always try to be conform.

Drama and toxicity, like animagusurreal mentioned, are problems too, but every fandom has that, that's probably not even unusual. You will always have people that sour the mood, especially when there are so much in one fandom and interests probably collide. Just look at Facebook, it's not different in terms of drama and toxicity when you look closer, maybe even worse. But I might be biased in my opinion about that.

And of course there are also just some assholes that don't respect anybody who is different than them, ignorants and racists. Such an unusual community will always be a thorn in their side, no matter what you do.

As far as preconceived notions: a sense of not just pervasive sexual behavior/themes, but a belief that that's all there is. I know a few people who stayed away from the community because they had no interest in sex rp'ing, and were genuinely surprised after dipping a toe in the water that it's just like any other community, really, just we have tails and such.

As far as my own observations from the inside: oh we like to **fuck** alright. Being a sfw furry is like occupying the thickness of a eggshell. You know there's an ocean of lewd goo just waiting to come out and get eaten up.

Addendum: There's also a baffling number of phobic, racist, nazi aesthetic loving, generally horrible people who are gleefully open about these things. The misogyny (while still terrible) doesn't surprise me as much because it's a historically male dominated social scene...like The Internet in general circa 1994 which most of these people still mentally inhabit. Listening to a self described green dragon wolf unabashedly disparage trans people still blows my mind every time though.