You have to optimize and test constantly for AdWords to pay off (disable content network advertising, geographic targeting on a schedule that follows the sun, a

You have to optimize and test constantly for AdWords to pay off (disable content network advertising, geographic targeting on a schedule that follows the sun, a/b testing copy) and build methods of retaining users that don't buy to eventually convert (email newsletters, add us on Facebook, sign-up for this free ebook, blah blah). My guess is small business doesn't have the time to tweak all these things. There are also small tricks about writing copy to make it economical. Social media sites have the retention mechanics built for you so I'm not surprised they convert better. Just my 2 cents as a guy who does marketing for some spare pocket change.