Classifieds traffic is huge if your niche pertains to the classified sites. For instance a site for automobiles. Furniture. The stuff that really gets searched on classifieds.
if you want to get tricky with it, you can do like I did, and post ads to craigslist selling cars that are dirt cheap, and have a directory listing on your site. you can make tons of money from ad networks with this traffic. Even AdSense. With adsense there's a bit of a redirection method with cloaking the traffic to make the source look legitimate. But if you think about it long enough, google some of the old affiliate marketing cloaking methods, add some redirects from your own site in htaccess, then you can disguise the source of the traffic so that they wont flag you.
I got an adsense account banned for craigslist traffic.
I know someone who just keeps duplicating the same site over and over and throwing a new name and logo on it, hires someone from India post to classifieds, and makes money from various ad networks. He has 20,000 sites that make in between $3-$4 a day. Do the math on that.
OFF TOPIC:And he drives traffic with scrapebox, and pings ecommerce websites, etsy stores, and etc. He sells SEO services btw.