if model X is paid to perform a modeling service and fails to comply with contract i don't foresee a problem reporting that he/she is in breach of contract. (if you are more comfortable having a lawyer post in "legal-jargon" then do so)
agreed! , "misdealings" are sometimes "resolved" posting a report will make others aware (buyer beware) and/or prompt an individual/company to take action in correcting this problem. (be very sure of your facts and post only the problem you encountered)
agreed! , the atypical "sandbox" fights are going to occur but i'm sure we all know the difference between "just" and "unjust" and maybe shed some knowledge/direction in resolving the problem ourselves. (dude! , you didn't get it in writing! , your screwed!)
and before i write anymore (i know you all are just hanging on every word that comes out of my keyboard!) the best person to answer this question would be someone in the legal field. (i should have either become a lawyer or an automotive mechanic , the fields are very lucrative!)

sincerely ~ ..."your no good"... - linda rondstadt