wrestle with a pig

"And when you begin refuting one another's reasons, fussing back and forth, you generally do what a nationally known industrial relations authority warns you against: you wallow in the mud with the pig. He says, 'Never wallow in the mud with a pig, because the pig likes it.' That is exactly what he wants, because you are on his home ground. He can think of arguments as well as you can, so where do you come out?"