Hi Roberta, I can feel your pain! I too, had gone out of my way to make the guest feel welcomed, when a recent guest insisted that I refund her and her family 1/2 of their rental fee because, she said:
1) my cottage was dirty (dusty), so much so her daughter had an asmtha attack
2) she claimed all of them had been "bitten" by some kind of bug, and
3) there was a bug and spider on the couch.
As you can imagine, this was all very upsetting to me. I was grateful that she contacted me with this before/instead of leaving a bad review. But still, being 4 hours away and unable to verify things myself, I agreed to contacting Airbnb and refunded her 1/2 of the rental fee. I had my co-host and house cleaner go over and look the day after she checked out and to contact me with what she saw.
Needless to say, I have always gotten excellent reviews, and my co-host assured me the cottage was clean, no bugs, and the guests had not left the cottage in the condition we agreed to in the house rules.
What I learned from this experience (after aggonizing over it for days) was:
1) You can't please all the people all the time (that's really hard for me because I love to please people and take great pride in our little cottage)
2) There were no bitting bugs. I have decided that they saw our dog crate that we leave for our dogs when we visit, and that they must have psychosomatically believed there were flees in the house. I will add a note in the house rules that we keep our dogs there when we visit.
3) We stayed a whole week at the cottage, two days later, and did an obsessive deep cleaning. Afterwards, I decided I would write a check list for my co-host/housekeeper so that we would have a record of what was done prior to our guests checking in (and so that we were both on the same page when it came to standards of cleaning).
4. Since we live in the National Forest, and bugs and spiders were a known enity, I would do a better job of scheduling routine pest control.
5. Repeat #1
While my situation with ridiculous guests was different from yours, I believe we can learn from those
experiences. And maybe find areas for improvement. . . even when you might want to initially kick the guests right out of your house! LOL!! Hang in there, there's always going to be a few people you can't please, no matter what you do.