In my mind you have a few issues to think about, but I always put it in the context of "Would I host this guest again?".
You are part of a community of hosts and it's important for hosts to get feedback from other hosts on their guests. You are also running a business and a poor review will most likely not create a repeat customer. This is the inherent flaw in the ABB model, the community wants accurate reviews, but the host wants repeat business. There are things you may tolerate as a cost of doing business that other hosts may not.
The simple answer is to be honest in a constructive way. A review for this guest that states “Bob was a great guest, after a misunderstanding on the number of guests he quickly responded by paying the additional fee, we hope Bob comes back again”.
If you think this guest was trying to pull a fast one and you don’t want Bob back again, it’s your obligation to notify the community of hosts.
Hope this helps…