I wouldn't overthink it, some people are bad guests just as others are bad hosts.
We had a cousin visit recently with his girlfriend and 5 yo son. They told us the 5 yo was developmentally delayed a bit. They didn't explain that he was delayed by approx 3.5 years, couldn't speak, understand instructions, had no impulse control, and basically spent the whole time running around, emptying shelves, boxes, drawers and breaking everything he could get his hands on. In between trying to keep the chaos to a minimum and comfort my daughter who was upset by having her things broken I cooked for them 3 meals a day.
DH went out of his way to provide activities to entertain the son and give the parents a break. Finger painting, music making, playdough, sensory bowls.
I went out of my way to help the gf, taking her for long walks when she was stressed as she said this calmed her down, cleaning up after them all as much as I could.
Then the cousin got a stomach bug and we basically had to find ways to avoid him coming into contact with the other 5 people in the small terraced house for the next 3 days when we managed to convince them all to leave early.
After which we all got sick, so clearly the avoiding didn't work well.
The girlfriend then had the nerve to complain that our house was messy (yes, it was, after you and your family trashed the place!) and that we didn't provide a stairgate. Which would never have occurred to us for a 5 yo and I don't think would have been safe anyway as he was a climber. She then broke up with the cousin and said he wasn't permitted to take their child to visit us again. I think we'll cope.