Onsight means that you make it first try and have no info, whatsoever, about it, except from what you can observe from the ground.
Depends how far you want to take it - I've been out bouldering with James and he's actually faced out from the crag whilst somebody does a problem, so that he can get a pure onsight ascent.
admire his "ethical purity".
If i don't flash a problem I work it to death-does this make me unclean?
Not what I meant really - bad choice of words on my part