Rule of thumb.... Assume all players are dudes, then when you join a guild with a vent you might be pleasantly surprised to find out that dude was a girl.
I find that assumption kinda rude.
I mean, I don't mind / care what gender a person is and I don't assume anything.
But when people send me tells like "hey man...." (actually happened yesterday) I get... well not pissed but it will get a negative reaction from me, how bad depends on my mood I guess
You can talk to people without forcing your assumption about their gender on them.
And yeah, I play female toons almost exclusively, it's all about being able to relate to my character.