Both of my cats died a few years ago (4 months apart) - the little one died on my sofa from cancer (he was 12), the big black one died of old age (he was 15 or 16). I would love to have another, but I can no longer afford any pets.
I generally don't answer that question. I always wonder if someone is going to ask to move in with me or is curious as to whether there is anyone stronger than me to defend my home.