A book without potty humor is like a banana split without hot fudge. It can still be good, I suppose, but you kinda get the feeling that something is missing.
While you're playing cards with a regular guy or having a bite to eat with him, he seems a peaceable, good-humoured and not entirely dense person. But just begin a conversation with him about something inedible, politics or science, for instance, and he ends up in a deadend or starts in on such an obtuse and base philosophy that you can only wave your hand and leave.