I want my brother and his girlfriend who are visiting to sleep on a pull out couch in the living room
You don't have an empty room they can use?
I do but I hate having guests in my house
You shouldn't treat your brother and his gf that way when she is visiting. She will paint you as a monster.
My home. My rules.
That your prerogative, but it is still a shitty thing to do. Just give them the guestroom.