Even though I more or less play one (I won't deny it, go ahead and scold me for it), lesbians of any sort. The server isn't as rampant with them as it used to be (To all you young-in's, in mid-Asulon the ratio of straight females to lesbians was about 1:3, not even kidding), but they're still a little bothersome to see sometimes. I won't try and justify Vithy too much, but at least she 'sort of' has a reason; She suffers from a god-complex disorder and narcissism, meaning she's attracted to herself to an extent where she more or less lacks a sexuality. Because of this, neither gender, yet at the same time, both genders fit her sexuality criteria, however, women represent herself much closer than men do and because she quite simply likes sex, she finds them more attractive (however, she has been known to sleep with men on several occasions :P).
However, what bothers me more (although I'll admit, aren't so overplayed these days. Thanks community!) are 'bisexual' characters that never interact with males. I noticed this a lot during the mid-Asulon les-plosion; There was a lot of characters whose players would claim were 'bisexual' but would only ever hit on females (Yes, Vith 'prefers' females, but she is still somewhat attracted to men). That bothered me more than anything, but thankfully, it stopped recently.