If the series is a single player series with tacked on multiplayer, and the single player leaves plenty to be desired, then pan away, let those scores drop. If a game like Gauntlet (may it rest in peace) or TF2 had a terrible single player, then feel free to use your hand to smack yourself in the face, because you missed the point of those games. If, however, a game touted with both single and multiplayer playability, with an actual difference between the two, has a terrible SP, then, again, pan the living hell out of it. I can enjoy games just for the multiplayer, but I don't always want that. Sometimes, I just want to do it on my own. If the multiplayer is the focus, and they tack on a crap single player just to boost sales, then I would also agree that lowering the score is acceptable.