Craigslist platform there are many categories and people posts thousands of posts daily to sell and promote their business by abiding Craigslist law. But some people does not care about that much. They posts unusual amount of ads in their targeted category which causes other advertisers problem and they makes other advertisers ads less viewed. So here is the solution, Craigslist has a by default feature and that is called Flag. When any user thinks a ad is not following Craigslist policy and rules they can report about it and flag that ad to be reviewed by Craigslist. If that ad is not posted with their rules then they delete it and other advertises gets priority.