Asking this as a guest with 10 years experience on the platform.
I've recently cancelled a booking 30 minutes after arriving to the apartment - realizing that it didn't match what I expected. Unfortunate but such things happen. The host got very upset with us despite getting paid for 2 nights (that was the cancellation policy, we spent a total of 90 minutes in the flat since he checked us in early).
Immediately after the cancellation (we checked out and left the key) he messaged me to say that this is disrespectful to him and he demands to be compensated, to which I replied that I'm sorry but he did get the money according to the cancellation policy.
Following that he left a negative review which isn't that bad "can't recommend" but flagged me as "disrespectful" and "unapproved guests". This part is what drives me crazy: apparently AirBnB support doesn't consider this flag as something that can be reported or removed. I can accept "disrespectful" as a subjective opinion but "unapproved guests" feels like something that needs to be backed with SOME shred of evidence.
I am now very worried that this will either hurt me getting approved by future hosts (even though I have 39 other positive reviews) OR that it can actually block me from features like "instant booking" which I use often to ensure I have a place to stay.
This is partially me venting and partially me asking if you had such cases (either as a host or a guest) and what's the best way to deal with it besides what I was told by support which is basically "ask the host to remove it" (uh, if communication could solve this we wouldn't be in this mess) or just hope that the other positive reviews are good enough (again - when I book a place I read ALL the reviews attentively and I expect good hosts to do the same).