Absolutely!
Think about it, so many pets are most comfortable in there own homes.
They are not exposed to 'unknown elements" (other dogs, animals , aggression, possible insecure surroundings, other hidden dangers)
Peace of mind for the pets and owners knowing they are in there surrounds, and that you ....being the awesome pet /house sitter that you are will provide the best possible care for your clients. Leaving the house "BETTER" than when you found it and following owners instructions to a T. Things do go wrong all the time in a home ( I used to house sit large luxury properties in CT) Hurricanes, Nor-Easters, Trees down, Road Closures, Major Snowfall, snowed in, Power outages, Hurricane Irene, no power for 11 days, I have seen it all while caring for pets in the owners homes. I was able to handle everything calmly and when the clients/owners returned all was back to normal and seamless. Again, all about peace of mind! Oh and if you have a pet sitter sign on your car, PLEASE REMOVE IT if sitting in others Homes..... :) s