If you were VAC banned, then it's across all games on your Steam account that use VAC. Better create a new Steam account.
Edit: Update, sorry, actually I might be wrong here. It seems a VAC ban on a Steam account bans you from all multiplayer games with the same engine. Example, if you got banned on TF2, you're also banned in Half Life Deathmatch, Counter Strike, Garrys mod etc.
Not sure if VAC recognizes Blackops 2 and Ghost as the same engine, since they all use updates versions of the IW engine.