Facebook exposes its advertisers to trollsNew Facebook ads play video and allow user comments. Inside Facebook's Justin Smith gushes over the new format, saying it has the "potential to drive much more engagement than any ad product on the site ever before has." Though that's not saying much, considering Facebook ads' notoriously low click through rates, we're still skeptical. Except for Valleywag's, of course, Internet commenters are trolls who hate life. Exposing Madison Avenue's clients to them is not going to make brands more comfortable advertising on Facebook. There's also precedent. Gadget blog Engadget, which for its size, does much better than Facebook with advertising, tried allowing users to comment on ads back in 2005. Called "Focus Ads," the product no longer exists.