A few weeks ago I wrote a post over at 68 Classifieds named Classifieds and Spammers which goes over ways to deter spammers using 68 Classifieds software. This post also got me thinking about building a web service similar to Akismet but made specifically for classified sites.
In the beginning this all sounded really simple until I thought about the majority of classifieds spam. Unlike email, people spamming classifieds seem to be placing real ads. To me it looks like they find a product on a site like Ebay and then copy and paste the text, images, location and then just change the price to something extremely low. Ads like this would be very difficult if not impossible to use some type of filter on. You would basically have to know the industry and determine for that listing the price is to low.
So I started rethinking a spam service and instead of using some sort of bayesian filter to instead use ip and email address filtering on the registration. I know this wouldn’t be foil proof but with enough people using it, it could generate a large list to check against.
I am mainly writing this to see what others think. If your site was as large as Craig’s List how would handle this type of spam?
