Keep it brief, factual and unemotional, @Megan158. "XXX was extremely clean. He did break our house rules regarding pets."
That would be enough really. And if he blasts you with a bad review, respond in a brief, factual, professional and unemotional way - and only to what is written, not to stars. For instance, if he writes about the wifi and the washer, respond with, "The wifi outage was due to the hurricane and was fixed as soon as technicians were able. The washer leak was repaired the same day XXX reported it."
That sort of thing. If he doesn't mention them publicly, don't bring them up, since prospective guests will only see you being defensive. His bad review (if that's what it is) will be buried in time with your good reviews. Being accurate and truthful is much more helpful to the system, and ultimately to you, than worrying about perceived negativity. By all means, concentrate on the positive, but be honest.
Hope this helps. I know where you are coming from: it is so easy to write a good review, and so hard to write a bad one.