Never sit watching someone coming in and say "This is not going to end well." If you can tell they have no clue what they are doing, get off your butt and offer to help them.
In the past two years we have prevented several families having bad vacations simply by keeping them from self destructing.
Examples
Couldn't get into my site due to a family trying to unhook in the site across from our. He put down the back jack and was using a floor jack to try to lift the front off the ball of the truck. No dice. Suggested he crank up the back jacks until he unhooked. this family was out for their first time. They didn't have advance reservations and had to move 3 times over 4 days. I moved it for them the last time.
In OC, MD this year. Had some French Canadians come in after dark to the site next to us. Two very nice ladies. The whole time they were trying to get parked not a lick of english was spoken. They were struggling. They couldn't get the 5er hitch unlatched. Finally I couldn't take it any more. I had to help. I suggested they put there wheel chocks (they called them stoppers) under the tires before their trailer ended up in the lake. Then showed them how to back up on the pin to unhook easily.
The list goes on.