We have been hosting for over 8 years and have had a number of guests (3 or 4) rate 4 or 5 stars across the categories and then rate overall lower at 2 and 3 stars with all this blurb about what was wrong with the apartment. This type of behaviour is totally unfair and unreasonable but yet Airbnb has continued to ignore the protestations of its hosts and make the rating a calculation based on the average of the individual ratings.
We have over hosted well over 500 guests in that time but yet our overall rating currently at 4.77 continues to fall because it is never reset. Mathematically any fool can tell you that it has nowhere else to go but down if it is not reset say, every 2 years!
Absolutely ridiculous! Without hosts Airbnb has no business!