It is the people. Before CL and eBay was the newspaper and local ads at the grocery store. I would get calls from people then a no show or the ever famous "your junk is worth a dollar" until they own it then its worth a million.
The bottom line is until there is an exchange of money there is no deal or commitment. Talk is cheap and cash is king. I personally have had successes and failures with all means of advertising.
Andy