@Sandra856 I save the guest from feeling terrible after the fact, and save myself from less than favorable ratings, by cluing them in at some point during their stay as to how hosts are affected by the star ratings. Most are appreciative of the information and ask why Airbnb leads them to believe that 4*s is good, if hosts are punished for them. I say, you'll have to ask Airbnb that million dollar question.
I'd never ask a guest to rate me 5*s, I just tell them how hosts are rated by the company, what will lose me my Superhost status, and hope they respond accordingly. So far, 2 and a half years of hosting and 5*s across the board. Fingers crossed.