Shares of Renren (NYSE:RENN) opened at a new all-time low this morning, and it's easy to see why.

The Chinese social networking website operator posted disappointing quarterly results. Bulls may argue that 47% top-line growth is nothing to scoff at -- and that posting a narrower-than-expected deficit after coming up short in two of the three previous quarters is a sign of improvement -- but the market isn't buying it.

Renren's in a funk, and investors generally are trying to steer clear of the areas where the company's doing well.

It's easy to call Renren "the Facebook of China" given its market leadership, but that's a crutch. It's also been more of a broken crutch lately.

Renren may have seen its revenue grow 47% to $50.4 million, but display advertising -- Facebook's (NASDAQ:FB) bread-and-butter business -- actually declined by 14% at Renren. The growth at Renren is actually coming from its online gaming and Nuomi group-buying initiatives.

Wrap your head around those two niches. When stateside investors think about social gaming, it essentially boils down to Zynga (NASDAQ:ZNGA). When the daily deals nature of group-buying websites comes up the leader -- and bleeder -- is Groupon (NASDAQ:GRPN).

Do these sound like compelling growth areas? It's probably not a coincidence that Renren, Zynga, and Groupon all went public at double-digit prices last year, and all three are trading in the low single digits now. It costs money to make a difference in online gaming and flash sales, and if you're wondering why Renren barely broke even a year ago but is posting a modest loss this time around, you're seeing the problem.

Cost of revenues soared 190% over the past year, and that's not good when revenue is only growth at a quarter of that pace.

Yes, Renren may be quick to point out that monthly unique log-in users clocked in at 48 million in September, 27% ahead of where it was a year earlier, but then why did the bottom fall out of its online advertising business?

Renren's guidance is another ugly sight. Bringing back flashes of Baidu's (NASDAQ:BIDU) disappointing third quarter, Renren's calling for a surprising sequential dip in revenue for the current quarter. Yes, the 37% to 43% year-over-year increase sounds good. Baidu's similar 38% to 42% top-line growth projection also seemed respectable. However, $45 million to $47 million will fall short of both the $50.4 million it rang up during the third quarter and the $51.1 million that Wall Street was targeting.

Then again, at least Baidu's very profitable. Renren's growth is coming entirely from models that have flopped closer to home.

And now you know why Renren's at a fresh low today.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.