I have had a friend and his son camp with us several times in our TT. These times were a lot of fun.
You have to be selective about who you allow to go with you (in your RV).
This friend takes care of my TT as well as I would. I once loaned out one of my cars to him for a week and it came back cleaner than I gave it to him!
There are other friends/family that I would not want to take. They probably wouldn't take care of the TT as I would want them to or they would not be good company.
I also bring a tent as kids usually WANT to sleep in a tent outside.
Some of our best memories were made when sharing the TT with others.
To the OP: It sounds like your friends just had a lot of bad luck on the trip. I would cut them some slack more than if they had trashed your TT due to being careless slobs or something like that.
Steve