rowan, you don't even know how VAC works. VAC bans you on the game that it suspected you of cheating on (or the game it randomly wanted to ban you from), not in any other game. If that would be the case (all games getting blocked by 1 false or actually proper V AC ban), then I would have already friggin' flew to the US just to friggin' sue Valve even thought I'm not 18 yet (would have asked my mother or some stuff).
EDIT: Wait what..? If it bans you from Source game then you can say cya to all Source games you have? What a shitty idea.