Another factor is the age/condition of the TT. Before we owned our own, my in-laws used to have us stay with them in their TT. But their TT was old, beat up, and smelled terribly of moth balls (used during the winter storage). Where we slept was cramped and uncomfortable. And I refused to use the toilet or shower, and had to go to the CG facilities, which was no fun.
That being said we have offered our TT to some relatives over the years, because we do not have a spare bedroom. They enjoyed their stay and privacy, even though they had to come inside for the bathroom.
In his later years, I could not offer the TT to my father when he visited, because he had a difficult time getting around and I didn't want him falling in or around the TT. Interestingly a few years before that, my father came camping with my family several times (5 of us total in a 24' TT) so it was pretty cramped for space. But he was used to tent or PU camping, so he thought this was luxurious living! By brother and his wife might be coming out east to visit us in the fall. Now with our 28' TT, I would not be hesitant to offer them the TT. Ironically, they themselves have recently started doing research on buying a small TT of their own.