I'm usually nice to them at first, and if they persist then i remind them that this is my job and i'm a person. haha, i usually ask them if they'd fix my toilet for free if they were a plumber for 'five gold bb'. if they're really being unreasonable or rude i'll remind them that 'this isn't the food pantry, if you want to see you can pay me'. which usually makes the other guys in the room who do intend to pay, or at least aren't being pricks laugh. I've def earned myself some favorites for being real to the jerks instead of just kicking them out.