My neighbours have a cat which they shut out at night. The cat has recently figured out how to work our cat flap, and when the weather was really bad, he would come into our house and sleep under the kitchen table.
It didn't bother me too much when it was -10 outside, though I would still chase him out in the morning.
I thought it would stop once the weather got better, but it hasn't. He comes in all times during the day now. He's crapped on my carpet, and my neighbours feed him on their kitchen worktop, so he wanders willy nilly across my kitchen surfaces. We spent bloody ages teaching our cat not to go on there, but we can't teach this cat, because as soon as we walk up to him, he scarpers. He eats my cat's food as well. As soon as I see him, I chase him out, but he comes back later when he thinks I'm not around.
Last night, I was woken by a loud crash. I ran downstairs thinking it was burglars, but no, it was just the neighbours bloody cat knocking a plate off the counter. Neighbour cat yowls if he is kept in the house, so asking the neighbours to shut him in isn't an option really.
Is there any way I can deter him, without bothering my cat? Anything I can think of to deter him would also impact my cat, and that's not fair.