Lots of 'We've never noticed a smell when we've taken our doggy to a dog-friendly holiday let'.
Of course you haven't, because you're used to the smell or just generally unoffended by it in order to own one in the first place.
I'm someone who is very sensitive to it (and in early pregnancy it was my worst sickness trigger). I can only think of one, possibly two dog-owning homes I've been in where I couldnt smell dog as soon as I've walked through the door (and one is huge rooms, high ceilings, all wood floors).
But, I've stayed in dog-friendly lets with friends who have one, and most are well-cleaned and geared towards minimising smells (no carpets etc).