Scenesters are effectivelyh people who follow any trend that has become 'cool'. For example, guys have started to wear black shirts, red ties, skinny black jeans and Converse because bands like My Chemical Romance or Green Day do. While it may be acceptable to dress preppily/smartly if you actually go to gigs, listen to non-mainstream music and actually involve yourself within a scene, scenesters just pretend to so that they can boast about their unbelievably cool state of indie or emo over everyone else.
Indie Scenester: 'Do you know about The Block Party? They're going to be HUGE, like, seriously bigger than Franz Ferdinand, but I don't like Franz anymore since they became big.'
Proper Indie Fan: 'Yeah, I saw them live back in 2003 supporting Interpol.'
Indie Scenester: 'Aren't Interpol that band that don't speak in their songs? God, instumentals speak to me in so many more ways that singing does.'
Proper Indie Fan: 'Whatever.' *Sighs*
Emo Scenester: 'OMFG I fucking LOVE MCR, they r the best band since Green Day cos the singer is SOOOOOOOOOO hot!! <3'