Entrecard, an online business card service and blog link exchange network that is as addicting as your favorite social network, is being dismissed by its critics because it could increase a website’s bounce rate, or the fraction of browsers that visits a page then leaves immediately.

This happens because many Entrecard members try to drop their cards — dropping a card means clicking on the “drop” section of a blog’s Entrecard ad space — to earn more credits that they could use in placing their own ads on other members’ sites.

Entrecarder “phirate” defends Entrecard by coming up with a new category of visitors called “commuters” and comparing Entrecard ads to highway billboards:

Now lets compare this to billboard advertising on a busy highway in LA. In terms of targeting, nearly everyone who sees the billboard lives in LA, just like we all live in the blogosphere. While the commuters’ professions may vary from lawyers to doctors to surfers, our bloggers fall into just as many unique niches. No one ever stops for long periods of time to look at the billboard, but that doesn’t stop companies from spending tens of thousands of dollars per month on them in high traffic areas.

Read this insightful article at the Entrecard blog.