So a player confided in me that she was a guy.
I replied that I assumed he was a guy by the way he talked and I added that there seems to be more female portraits, than males
He said that he flirts with the men to get RSS and help with runs, etc.
Do you think this is fairly common?
Common in games yes. Some for getting sugar daddies and freebies. And getting into good teams/guilds Etc, lotsa perks. 
I’m going to use my brother as an example. When he has the option to choose the gender of his avatar in a video game, most of the time, he’s going to pick a female character, because that’s what he’d rather look at. (I don’t have a problem with this since half the time I choose the male characters for the exact same reason).
It could be that the person in question simply likes how the female avatars look better than the male ones. Gender doesn’t necessarily have anything to do with it.
