I'm not sure I know what the story wants to be about. You can read it at more than one level but it's hard to find one that really works. This is a bit sad, cause I've read Brown's "I never liked you" which does incredible job of depicting ambiguities of human feelings and in comparison "Paying for it" looks pretty blank and heavy handed.

Author explains that he removed a lot of interesting human details about his 'partners' to protect the women's anonymity - what remains renders the portrayal of the women and their relations with Brown even more superficial than they most likely were in reality. Chester Brown as author/protagonist is torn between being a subject of his own depiction - one uncongenial individual with complicated history having a bit of trouble making a connection between sex and feelings and a kind of social thinker trying to sell his views on the nature of human relationships as objective and rational. In this he comes out as a very stuborn person unwilling to accept the complexity of the subject matter. In the appendix he discusses various arguments against prostitution and while certainly he makes a lot of valid points, his urge to win the match 10:0 is a bit sad.

I could say that "Paying for it" is good as a story of a zealot, but it doesn't really tell you more about such people than 5 minutes of reading comments under any news or article in the internet. Anyway I'm going to read "Louis Riel" by the same author and hope it'll be a better experience.