Unlike all of you, I can quick scope and snipe regularly. =]
I just can snipe in general.
Quick-scoping is basic sniper techniques in video games. You can't afford to stare down the scope all game, yet its a bit tricky to no-scope with accuracy consistently (especially when most sniper rifles have weak hip-fire accuracy). Quick-scoping combines no-scoping's aiming technique with a brief flash of the scope to tighten the aiming reticle's movement milliseconds before the shot.
Quick-scope puts the "pin" in pin-point accuracy. No-scope puts the "point".
It's not hard to be a sniper. It's hard to be an amazing sniper though. Close and mid-range will really test your skill level.