The last few weeks have seen a rally in…well…for lack of better word, “crap.”

Before Tuesday’s correction, Research in Motion (Nasdaq: $RIMM) had risen 37% since just the beginning of this month and had nearly doubled from the low hit over the summer.

Facebook (Nasdaq: $FB), the company that may be remembered as the most disappointing IPO in decades, is up more than 36% in just the past two weeks.

Even Dell (Nasdaq: $DELL), the perpetually cheap PC maker that has struggled to stay relevant in the age of cheap Chinese competition and from upstart tablets and smartphones, has shown signs of life. The stock is up 13% in just the past week and a half.

What’s going on here?   Do investors really see value in these tech disappointments, or is this just the mother of all short-covering rallies?

It’s a little of both.  Let’s take a look at each company separately.

Research in Motion has been a real frustration to me as a former bull.  This was the company that invented the smartphone and as recently as a year ago could have remained the dominant player in the corporate market had they played their cards right.

Alas, they didn’t play their cards right.  In fact, they didn’t really play their cards at all.  For the life of me, I can’t figure out what the company has been doing for the past two years.  BB10—the new operating system that is supposed to compete with Apple’s (Nasdaq: $AAPL) iPhone and Google’s (Nasdaq: $GOOG) Android phones—is scheduled to be released in February of next year.  That’s almost a year later than originally planned, assuming they meet the deadline.  And given the company’s recent history, that is not a certainty.

You almost have to work to screw things up as badly as RIMM did.   Even after the company started to fall behind its rivals, it had assets of real value.  Its BBM messenger is still the best texting and instant messaging program on the market, and it could have been monetized as a standalone app for sale in the Apple and Google app stores.  But it wasn’t, and every day that passes it becomes less relevant as its pool of current users dwindles.

I still see value in RIMM’s Mobile Fusion platform, which allows corporate IT departments to manage iPhones and Androids on the equivalent of a BlackBerry Enterprise Server.  But there is a very significant risk that the company will fail before they have time to fully develop this.

RIMM still looks cheap—on paper.  It has roughly $2 billion in cash and an estimated billion or so in patents.  Backing these out, the value of RIMM as a going concern is currently only about $2-3 billion.  A good activist investor could buy RIMM, chop it into pieces, and sell off its parts at a profit.  But before that happens, management will probably destroy a lot more value first.

It’s simply too late for BB10 to save RIMM.  A year ago, I think it would have had a chance.  But at this point, the company has too much baggage, and they are fighting for turf among the business crowd with a resurgent Microsoft (Nasdaq: $MSFT). (See “Microsoft Will Crush Google“)

Don’t get drawn into RIMM.  It’s a sucker’s rally.

But what about Facebook?

My wife and I have a rule of thumb for technology products.  Once our respective mothers use it, it’s over.  This is not to say that the company is going out of business, but its high-growth phase is clearly over.  When our mothers are using it, there is no one left to join.

Well, both of our mothers are now avid Facebook users.

You should take my “Mother Indicator” with a grain of salt, of course.  But given that Facebook trades for 40 times next year’s expected earnings, my concerns about growth start looking valid.  Facebook’s profits would have to grow at torrid pace in the years ahead for that valuation to be anything short of ludicrous.

Zuckerberg & Co. are anything if not creative (“ruthless” is another word that comes to mind), and I have no doubt that Facebook will find new ways to monetize its assets.  But the company depends mostly on paid advertising, which is not a proven model yet in the world of social media.  And rival Twitter seems to be getting more buzz these days.

Facebook is a $50-billion company with a questionable business model trading at a nosebleed valuation.  If you buy it, you are betting big on Zuckerberg’s ability to innovate.  I’m not willing to make that bet at current prices.

Finally, let’s look at Dell.  Dell is a good company in a terrible industry.  They make good computers and laptops, but both are commoditized products.  There simply isn’t much premium to be charged for selling a “good” PC these days.  All of the profit goes to Microsoft, the maker of the operating system, and Intel (Nasdaq: $INTC), the maker of the processor.

That said, Dell is ridiculously cheap, even for a seller of a commoditized product.  It sells for just 6 times expected 2013 earnings and for just 0.29 times sales, and at $9.77 per share its price is barely above the crisis lows it hit during the 2008-2009  meltdown.

Dell also has no net debt, a respectable return on equity of 27%, and a dividend of 3.4%.

There is a lot of bearishness towards Dell for the same reason that there is a lot of bearishness towards Microsoft and Intel.  Computers are no longer a growth industry. While I consider them far from “dead,” tablets and smartphones are creeping deeper and deeper into territory once dominated by PCs.   Investors simply have no interest in owning shares of yesterday’s tech darling.

And herein lies a potential opportunity.  Dell is interesting contrarian value play.  If you believe, as I do, that there is plenty of room for PCs, tablets, and laptops on the desks and in the lives of most consumers, then Dell should have a viable future.  And given that no one—as in not a single investor I have met in years—has any interest in owning Dell right now, your downside should be tolerably low.

If sentiment improves even modestly towards PCs, Dell could be an easy double over the next 12-24 months.

Disclosures: Sizemore Capital is long MSFT and INTC.  This article first appeared on InvestorPlace.