a bidder not paying is given negative feedback thereby eliminating any future business with the individual. it effectively "outs" the user as "bad business". the system cleans out the bs by self policing the community. a cc on record should be a requirement. any trading platform with feedback has to be given time to establish itself and as such no feedback or low feedback users must be approached with caution. the overall benefits for feedback systems far outweigh the negatives of new user issues.