Maybe the location. And I'm not sure some of those aren't sets.
As for "small portion" I'll only assume that you and I aren't even remotely thinking about the same thing ... I'm talking about personalities, Jared and Brandy's interaction with each other, the Sheets jokes, etc. etc.
I don't believe the show is scripted, but I do believe the show is set up ... It's a bunch of guys ad-libbing their way throw a show that has been given a general direction by the producers (including planting cool stuff in pre-picked lockers). It's not even clear to me whether there is real bidding going on the day of show taping because shot setup, etc. will take a big chunk of the time. But I'm certain that only one of the shows stars is allowed to win the pre-picked lockers. How would it look if joe six pack came in off the street and took one of the really cool lockers - the producers would be out of a locker and have nothing to show for it.
It's 30 minutes of escapism TV and if anyone thinks "reality tv" is real just doesn't get it.