Aside from the First 48, I don't think there is a real reality show.
My buddy got paid several years ago to be on Cheaters. Cheaters was initially real and funded by some holy rollers. Then the guy got stabbed and they went to all paid actors. My buddy got $250 to be the guy that a girlfriend was cheating with. It was ****ing hilarious as he had a little BMW hatchback that was in shitty condition at the time, and all the shots were dark so they narrator described it as a "snazzy sports car".
He also took some type of medicine to induce vomiting (apparently stage actors do it all the time
He gets hit in the gut in the "confrontation" scene and pukes. Said he'd never take that stuff again for a role. It made him feel shitty for a couple days.
To top it off, they weren't supposed to use his real name and they did. They just misspelled it.