Well let me ask a question (and I don't know the answer to this, but you probably know more).
But even if free advertising doesn't generate leads, is it possible that it will help Search Engine Optimization. If you have a link to your site on a free site that is related, even if it doesn't generate direct leads, if the page is indexed in search engines maybe it will help you overall.
Now I'm not sure if craigslist is indexed, I think I have seen some random pages in searchengines from CL, but I'm not sure.
So I guess what I'm asking is, even if you get no direct leads from free advertising, can it lead indirectly to improvements in
SEO and leads indirectly (ie. someone searches for brooms on google and maybe your craigslist post about your broom appears in the search results).