Usually they take off the glasses and change clothes and become amazingly beautiful. At least in the movies.
They actually did have a season of Beauty and the Geek where mid-season they sent in a female geek and male stud (but just one couple) to mix things up. You can imagine the sparks that ensue (I had to imagine them because as enjoyable as the show is it is also too terrible to watch for a sustained period of time).
My first girlfriend was a hot geek, valedictorian of her class, X-file fanatic, etc. and I think she works in the comic book industry these days somewhere on the west coast.
I'm a distant cousin of Singaporean pop sensation Dìck Lee. Bruce would have been a lot cooler but I'll take it.