do your friends and family often carry dog dirt into your house? Most responsible adults (which i'd hope your visitors are) would wipe their feet before entering your house and when doing this would notice if there were dog dirt on their shoes.
we all have carpeting that costs a lot of money, sofa's and electrical items too but how far do you go? I have a cream leather sofa that can absorb dye from dark trousers, It was my choice though and i've yet to ask a guest to remove their trousers before sitting on it.
they dont as i have a variety of clean soft slippers in my hallway that they put on before comming into my house