It never really bothered me. I've heard people preface a statement with "Dude" in place of "Hey, guess what", and once or twice a male friend has called me "Dude" in a way that seemed almost affectionate. Sort of like he saw me as an honorary "one of the guys". I'm neutral about that, though. My internal reaction is sort of an, "Um, okay.". If I know the person well, and if it clearly isn't meant as an insult, I usually won't take it as one.
I would be livid if a guy ever addressed me with "Hey, (female dog)!" That actually happened once, and I looked over my shoulder to see who he was talking to, even though it was clear that he meant me. I replied with, "That's not my name, and you're on your own."