Black Ops has had its share of glitches, but it is updated far more often than MW2 ever was so they are patched out quickly. MW2 was basically abandoned due to the implosion of Infinity Ward/Activision, which is why there was hardly any DLC for it (relative to being such a huge selling title) and very few updates to fix known glitches.

Didn't play WaW, so I can't speak to that one.