For example, those "home remodel" shows where a home is redone for a poor family and every single time, the family is introduced to their home "makeover" in which the adults sob and cry and the children run through the house screeching and hollering with joy. Every emotion is predetermined ahead of time and it often takes several takes to get it right. (So in reality, the family is seeing their "new home" for the 7th or 8th time in the version you see on TV).
It's an insult to the intelligence of those watching at home.
About the only reality show that is mostly not scripted is the long-running show "COPS" - which pioneered the genre. However, the in-between-call banter in the squad car, where the cop invariably blabs about how he "always wanted to be a cop", is definitely rehearsed ahead of time.
“The First 48” is pretty good.