@JB-And-Lexy0 It is simply because the overall rating is its own category with a score. You can get 5* for each other category and a guest can still give 1* overall!
Out of all my reviews I've seen maybe a couple that have a different rating in overall. I've had 4.84 overall for over a year (my best guess) and 98% of my reviews are 5* and it does not change. I think the system is not working correctly.
After many phone calls asking Airbnb employees, the system calculates de OVERALL rating that is displayed in our Properties. No one knows how it is calculated, but it is not an average of all of the Overall Ratings given to us by our guests...or is it?