I've learned that there is no reality show that is "reality". When the people on the reality show know there is a camera rolling, they will not act 100% natural. They will act, and think about what they are going to say/do more.
A couple I'd disagree on are the two I watch the most, Deadliest Catch and UFC. I'd say Deadliest Catch is about spot on because there's not a lot of acting that can go on when it's 20 degrees, snowing, sleeting with the wind blowing 60 and the seas throwing you around the boat. Just do your job and hang on. That's reality enough for me and for some reason, very entertaining.
The UFC, if you don't watch it, takes a bunch of up and coming fighters and puts them all in a house for 6 weeks while they fight their way to a UFC contract. They divide them into 2 teams, which does cause a whole hell of a lot of drama, but at the end of the day, it's really every man for himself. I'm sure there's some hamming it up for the cameras but the "reality" is, these are some mean, bad ass mother truckers who fight for a living.