What do you tell the owner if you had a bad experience with their dog and they want to book you again?

Hi! What do you do if you had a really bad experience with a dog you watched and the owner keeps wanting to book you because they literally go on vacation like every weekend? She's been sending me multiple booking requests. Thankfully I've been busy and booked watching other dogs and told her I was busy doing that. The dog is sweet, but I did not like her because she smelled really bad. I did not spent any time with her and I wanted her to leave. It was only with me for 3 days, but it was the longest 3 days of my life!! They never wash it or take care of it because it has a back problem. It probably has flees. And it has aggression and tried to bite me when it goes to sleep. It's not a good dog to watch on rover honestly. What should I do? Anyone else have this problem? I would love to pay and take it to the groomer because it smells so bad and never gets a bath, but I'd prefer to never watch it again and watch other dogs that are better taken care of and that I can have a better experience with. :)