My Uncle/Aunt owned a stunning holiday cottage in Cornwall (I say holiday cottage but in reality they bought it post retirement and spent 50% of their time there).
They were incredibly generous in letting my parents (DU's brother) and myself (plus DH and children) stay there on a few occasions for free. In return we always not only left the place spotless, but offered to do any odd jobs/maintenance whilst we were there by way of thanks (I painted a gate one stay and DH put in a new kitchen tap another - that sort of thing).
To be clear they didn't rent the place out when they weren't there because it was their home from home and didn't want strangers using it (and as such left a lot of their possessions there).
Two years ago, after being heavily pressured/pestered they allowed the daughter of a supposedly close friend to stay with her family for 4 nights.
Apparently the only time she could go was when DU/DA had planned to be there so as well as offering free accommodation they also sacrificed their time at the cottage.
I'm guessing you are all ahead of me here....it wasn't a family holiday but a hen do for the daughters best friend.
When DU/DA arrived the day after they had left they were distraught. The cottage was a state. Red wine stains on the carpet/soft furnishings. Filthy bathrooms/kitchen and broken mirror cabinet in the former. Curtains torn down in the lounge, the wooden floor in the hall/dining room ruined from stiletto heals, bedding stained with make up, DA's clothes had been used/tried on and smelled of smoke, the zip on a very expensive dress broken, fag ends tossed all over the patio etc. I could write several paragraphs about the damage (they sent my DF photos and we were really shocked, especially having been there and knowing how lovely the place was).
It took 5 days to clean up the mess and £££ to repair/replace the items damaged. Over a month before everything was back to rights.
The friend and her daughter refused to apologise or make any financial contribution to the damage.
DU/DA decided to sell soon after as they felt their home/possessions had been violated much like a burglary and staying there upset them afterwards as it reminded them about what had happened.
So no, A is NBU and I'm glad she is standing her ground because otherwise I think she can expect the same or worse than my DU/DA experienced
.