@Marianne51 your observation is probably quite correct.
When these ladies planned this vacation, they probably mentally pictured some relaxing days of sitting by the pool, enjoying the warmth, and torturing their host.
I can imagine them bringing some pre-written complaints, just so they could be rolling as soon as they touched down....
(Separate tip I have heard: keep the host response short, and there is no need to bring up complaints that the guest does not mention in *their* review. For instance, the guest's review does not mention the 4th burner, the bugs, and the bites. If your portion had not mentioned these issues, they would not be in anyone's mind.)
I hope it is a long, long time before you have guests this unpleasant again! (Ideally never.)
I am sure the great reviews from your normal guests will soon bury this person's review under an avalanche of 5-star ratings.