I'm sure I'm not alone on that one, I've met alot of Dunmer fans around here. (My favourite race are infact Nords, but that ain't stopping me from loving my second favourite. )
However, outside of the forums, I usually meet folks who find Dunmer less attractive because of the eyebags and such, which makes them look older in their opinion.
I disagree myself, I think Dunmer can look just as young as any other race. It's just the case that those eyebags and the harsh browline are a natural feature of the race, which means that it's just simply there, and has nothing to do with age. I embrace those features, and I think it's a really cool trait that makes them look more eccentric as a race, not uglier or older.
I sometimes make characters that I don't plan on playing, simply because I like to experiment with character creation. And in all fairness, I have no problems at all when making Dunmer women that would look like they're in their early to mid 20's and good looking. Granted, I find it more difficult (Although possible) to make male Dunmer look as young as their female counterparts, but that doesn't bother me anyway because my male characters tend to be in their 30's or 40's, but even then I think a male Dunmer can look good in a more rougher and masculine fashion.
In the end, beauty is in the eye of the beholder, ofcourse.
Edit: Ofcourse, I'm well aware that I mainly mentioned age in this thread. It's because I think that this is the main concern that people have with the Dark Elves. In no way am I saying that being middle-aged makes a character less attractive.