Best bets on TV

“Desperate Housewives” (9 p.m., ABC): Why can’t we all just get along? On “Desperate Housewives,” Susan and Katherine continue to fight over Mike, and now it’s getting physical. Just don’t mess with the hair.

“Dexter” (9 p.m., Showtime): On “Dexter,” Rita discovers one of her husband’s secrets and starts to question how much she really knows about her mysterious man. To which we ask: Where has she been all this time?