If they are going for realism, then it has to be done good, if not, meh. Games like Quake, Doom, Duke Nukem, Final Fantasy, Borderlands, and many more can do with completely unrealistic stuff. But Medal of Honor and Call of Duty need to at least try to be realistic. Crysis is a good example of bad realism. When coming out of cloaking the enemies around don't notice me right away, even if I'm right in front of them (good). Boats and helicopters, on the other hand, can seem to pick me out instantly, even when I'm in cloaking (bad).