Native ads -- those that are disguised as content -- may not be the answer marketers are looking for, according to a survey by Harris Interactive conducted for MediaBrix. More than half of those polled said native ads "negatively impacted or had no impact on their perception of the brand being advertised," writes Lucia Moses. Sponsored video ads fared worst in the survey, with Facebook's Sponsored Stories and Twitter's Promoted Tweets also neutral to negative. A Facebook representative criticized the methodology and pointed to examples of higher engagement via Sponsored Stories.