As others have suggested, when someone asks tell them you can recommend a local hotel/B&B. Visiting can create problems.
I recall when a friend moved to Spain she telephoned and said she was feeling lonely and would I like to go and stay with her for a week. Whilst there I would wash up after every meal, do my share of tidying the house and would pay when we went out for a drink or a meal.
A couple of years later she asked if she could come and stay as she was looking for a place to buy in UK. Of course, I said yes. A week before she was due to arrive she announced she would be bringing her new man with her, whilst here she never lifted a finger, never washed a plate, would sit watching TV while I prepared and cooked meals and when I walked past their bedroom the room was a shambles (no I didn't make the bed for them!).
On their last day they offered to take me out for dinner - we arrived, a pub not a nice restaurant, she took one look at the menu, declared she wasn't paying those prices and we ended up with fish and chips which we ate at home, with me washing up after (and supplying the wine). I have never invited her back!