I think most of them are.
Think about it. If someone followed you around all day with a camera, would you be entertaining? If you watch many of these shows some of the situations are too unbelievable for what mundane living life has for most of us.
If they aren't staged outright, then they are using the edited materials to make things seem more exciting than they really are.
Which shows do I think are really staged? I think AMC's "Comic Book Men" is mostly staged. I think many of the "Storage Wars" are staged. I think that most of the shows that have anything to do with bidding and selling of real estate and antique items are staged.
Why? Because it's unbelievable. It's rare that someone has a priceless bit of art in their basement, collecting dust. It's rare that someone is keeping incredibly expensive pieces of material in a storage locker and forgets to pay his bills.
All of these things are done to make couch potatoes watch like voyeurs and be fascinated by the human condition written to be more interesting than what it really is - an illusion.