I have never run into that problem...... but everything that happens to us using Airbnb does help with the sifting and sorting process we use before accepting future rentals. This is why I don't use instant book.
I use my home for larger family rentals. I have found that wedding groups are great. They have plans for meals and places to go. Funeral groups are awful. Nobody knows who is in charge; they are coming and going like zombies, and they leave a mess.
Reunions can go either way depending on who is in charge. I have learned to always communicate all of my concerns with the credit card holder. I have learned on occasion it can work with a person bringing their dog - a family dog. But if a guest who is not the credit card holder wants to bring a dog, I say no.
I have also learned that larger organizations, like for a race or a "cooking" group, etc., sometimes my place will be booked and the credit card holder isn't even one of the people that are there, so it is another thing to check.
I also ask about elderly and children so I can see if it is a good match.
I also ask for maximum people and maximum cars at any one time, so even if they aren't having a "party", I don't have parking and trash issues for larger groups.
Basically, I ask why they are coming to VT and how they plan to spend their time. I have learned to do it in a nonconfrontational way, I think.....