Might be the fact they just start talking portuguese like if it was the main lang in the whole universe,
or the times that they msg you like this: oi, br?, manu fri itanz plx, & some other shit i wont mention,
maybe there are other reasons like the fact that they think they own the game.
Anyways as you said you had a "good arsenal" of gurls, we admit it,
but i dont really imagine it would be a "turn on" to a brazilian girl to tell her:
I own a tibia account lets hang out sometime.. LOL no ofenses, some of my best friends are brazilians
and even they admit most of the br population playing tibia is just annoying.