I've seen it from both sides - I ran a kennels/cattery and when I left I set up a pet sitting business (in the eighties before such things were common) as I met lots of people who didn't really want to leave their animas but there was no alternative. The security aspect of the house is a bonus, with lights being on and someone closing curtains and picking up post. From the animals point of view, they are usually quite happy in their usual routine and as long as they get fed they are quite happy to sleep most of the time. However, if I was going for more than a couple of days I would always put mine in a kennels or cattery, for peace of mind, as I have known pets go missing while the owners were away and you have to trust that the person does what they are supposed to do.