Airbnb doesnt protect the hosts. Protect the business. This is clear. Airbnb doens't care about your rules (in your own country or in your own house), airbnb care about the business.
SO, in my experience, i got bad reviews only from bad (very bad , annoying, demanding) guests, which does'nt appy the spirit of Airbnb (if any spirit is left). People who dont understand what it meas to be hosted in a private house, what is the difference between hotel, bnb and home rentals. They (the guests) know that they have a big power in their hands: the review.
Airbnb doesnt control the review. They say "if the review comply the rules is correct" . But airbnb doenst consider as rule the authencity of the review. Airbnb dont care if the guest invented the review. Airbnb dont consider offensive when the guest lies.
I had an american guest who started complaining before to arrive. She started to "not understand" before she arrived. She started to demand before she arrived. And she continued for the first 24 hours (after she arrived) to bomb me with a lot of email , questions, demands, instructions..
In 8 years i never had such type of guest. I informed airbnb that this guest was "weird" and to protect me against any bad review. I asked airbnb to contact the guest to ask them if they were still happy to stay. Silence..
I got a bad review and airbnb, wihout investigation, accepted the review. 1 star. My average reviews for this fantastic falt is 4.8 stars.
Unbelievable.
Guests have the power. Stop. Be aware.
Regards