after this experience, how about : "no pets" in your house rules.
That would easily prevent some future troubles I believe, especially as you cannot be there regularly.
Can you possibly still edit your long reply to Nadia ? It does more harm than good.
If you gave it one extra day between check outs and check ins, you could make it your business to personally inspect the place and really make sure it is clean. Then if people say no, it wasn't clean, you can face them with much more conviction and authority...
And please, lets all write honest reviews on our guests: instead of praising them, lets be polite but clear and honest about certain things they have done that are out of line. It will help the next host, it will remind that guest of some possible consequences, and it preserves our integrity.
Ps : Your place looks great - and all the stellar reviews you have speak for themselves.