@Delilah, I second that emotion. As an editor who assigns and makes hires, I would put anyone who featured Demand sites on their resume at the bottom of the pile. Similarly, although writing under technical constraints and on deadline is good basic training for journalists, professional bloggers, and sundry content providers, the resulting clips are worthless.
Same goes for Groupon copywriting "clips." No matter how many gallons of blood and tears go into each chunk of Grouponese (and I've heard stories), the ads all sound the same to readers because they're designed to. Young writers should make money where they can, but take strenuous care to blanket the internet with their quality, bylined writing if they want a ghost of a shot at a real writing or editing job someday.