Most players don't actively roleplay in World of Warcraft -- however, it sure seems like some people do without realizing it. Tabards, when not being used for reputations, are usually picked for cosmetic reasons, as are mounts and non-combat pets. Faction loyalty can be seen as another type of roleplaying. A lot of people seem to hate Garrosh, even though his character doesn't actively affect raiding or PVP.
Personally, I like to think about what my character would think of things. I might not roleplay in game, but I know his political opinions. I've created some backstory for why he feels the way he does and why he became his class. After seeing his mother die, he knew he had to be a healer, and the priesthood seemed the best choice for someone distancing himself from the more barbaric ways of the Darkspear. There are even some quests I've completed that I've felt my character, story-wise, would never have actually done (such as killing Alliance members without provocation). Despite these tendencies, I don't actually engage in any roleplaying in the game.
Do you ever do any kind of roleplaying, even if it's in your head? Have you thought about your character's personality or history? Do you ever think about how your character feels about the various faction leaders and the recent changes in power?