@Rebecca
When I started I did a newbie mistake of rating everyone great (when sometimes a couple guests deserved 4 stars not 5) as I was afraid of retaliation that I’ve read by other hosts when they were honest. I did message people personally if there was an issue first thanking them for booking with me then suggesting if something had broken we would appreciate it if they would have let us know so we could have a heads up to address it before a same day turn over, another time it was a gentle reminder that we do have a no pet policy as we have an owner who has severe allergies and guests who are sensitive as well and we noticed an excessive amount of pet hair in the place (in the mattress covers, closet and more - more than if someone had a pet at home and hair was on their clothes that they wore here) - we had no direct evidence other than a ton of animal hair left behind. But these things were not in the public review.
I have learned from the boards that being neutral and factual if things didn’t go well is key to helping other hosts out when rating guests. Honestly there were only a couple of guests we would not like to host again and it was for issues related to being difficult/demanding guests or completely messy when leaving (we had to deep clean the kitchen hours after - I didn’t send in a claim but it was a pain to deal with; they were rated accordingly).
It is a fine line between being honest and factual without upsetting a guest to have a potential retaliatory review for some (reference some postings here on the boards).
Overall, we’ve had great guests that have been a pleasure to host!