@Kateřina0
In reviews, I generally try to refrain from explicitly mentioning things in a review that are of a personal nature, or which could embarrass the guest, but at the same time, I think it is fair, if the odor was quite bad and/or continual, for future potential hosts to know that your house smelled bad after this guest departed, or even during the whole stay if that was the case.
So...I would not mention anything about how often the guest bathed (which you can't know for sure anyway...they may have used the same towel over and over) or the state of the guest's hair or beard, or even that the bad odor the guest brought in, was his own body odor. Rather I think the point to be made, and which is fair to make if it bothered you enough, is that the guest caused (in some way) a bad odor to be in your home.
So maybe you could say, "George and Patricia were a friendly couple, nice and respectful people, and my cats liked them. The only problem I had with their stay, was a bad odor that stayed in the room after they left and after I cleaned and washed the room, which made it awkward in welcoming the next guest into the room. Hence, I reluctantly have to suggest that George and Patricia, nice as they are, might be better suited to stay in a hotel."
I add the line about the "next guest" because even if you didn't have another guest coming right away, it helps guests (and hosts) understand the consequences of someone bringing and leaving a bad odor in your house, to show that it not only affects you and your own comfort in your home, but potentially damages your business. By not stating in any way that the odor was body odor, you protect the guests from being embarrassed, but at the same time, by mentioning the odor, you indicate to the guests that if the man has a body odor issue, if he wants to stay in a private home, he should be very careful to use good hygiene and keep clean to minimize the odor, or he should stay in a hotel instead. I add the line about you suggesting they stay in a hotel, because it helps indicate the severity and impact upon you of this odor problem you were left with.