There’s a big difference between “guests” and “visitors” IMO. Guests are people staying over. Visitors might come over for coffee or a drink or dinner. Certainly there have been reports here about sitters “taking the p—” and essentially having their SO or family member or friend come crash at the home most or the entire time.
I had one sit where the HOs made a point of saying I was welcome to have a guest (stay over). My friend stayed over, and that was invaluable as the rescue dogs were a lot of work, and she was strong and a dog person. Of course, I cleaned the sheets and remade the bed.
Other sits, I’ve been welcome to have visitors come by for dinner or to use the pool/have a chat. Always on the up and up and never more than 1-2 people.