The most I can say is that a lot of people play Mario Kart Wii online split screen. Often half or near half of the players are guests (and you can see they vote for the same track in pairs).

Yes that annoys me especially when they vote for a track you don't like.

There's no online culture, it's just a random online play

well if they could speak in most games, i doubt they would say something much different than XBLA and PSN users. The behavior depends on the game.
Mostly, they are honorable.Some do cheat in specific games, like MKW but are just a tiny minority compared to the vast playerbase. I dont complain much. I think TC was pirated heavily because it has many more hackers than COD reflex, a game that sold many more copies yet is much harder to find a single hacker. So certain games, that are too pirated AND online, often show poor online sportmanship.