[DeeKay]

If you've been betting all flops where you were the PF raiser, and now you check a KKx rainbow board, I think it lets the villian know, "hey, I'm repping the K by NOT betting it, 'cause I've CB'ed every other flop...". OTOH, if you've been playing more straight-forward and not bet every flop, I'd be more apt to bet here, especially if you've been shown to bet your hands and check when you whiff.