“Everybody has a secret world inside of them. All of the people of the world, I mean everybody. No matter how dull and boring they are on the outside, inside
them they've all got unimaginable, magnificent, wonderful, stupid, amazing worlds. Not just one world. Hundreds of them. Thousands maybe.” -Neil Gaiman
If you equated it to confidence like the first poster stated, going off the affirmation of sexiness, then we're getting somewhere. However, I see it also, as being related towards the ones who wish to be confident, picking a sexy avatar in which to get the affirmation they desire.
If sexy avatar means a sexy poster, then other aspects of avatars must also be reflective of the poster.
Mine is a magician playing to an empty house. Does that mean my whole life must be like a Tom Waits song (also supported by the fact that my first avatar was of Tom Waits)?
Really, though, sexy avatar probably doesn't mean sexy poster. In fact, isn't the standard response to someone having not just a sexy avatar but a sexy "picture of themselves" to assume that picture is fake and they are either an old creepy man, some teenage boys playing a joke or a very overweight middle-aged woman who has a big collection of those weird ceramic children?
So maybe sexy avatar=trying too hard to seem sexy, is not sexy at all.