@Matt2, note all your stars as they are today on a sheet of paper or in an Excel list. After every guest, you can compare the numbers of 5 stars, 4 stars etc and note them wih the name of the guest. That's useful if they return.
But it may cause depression from time to time.
For your last guest, you see beside every category a phrase like: Concratulations, your last 4 ratings in Cleanliness were 5 stars.
Or your last rating was 5 stars.
In both cases you got 5 from them. If there is mentioned: You got 5 stars x% of the time, that means you got them before but not this time.
As said by others, the messy types usually note you down. I came to suspect that all guests rate themselves. Or they rate the state of the place at departure as they have forgotten how it was at arrival, what also means they rate themselves.