What brings together miniature display imaging technology, gaming software, and solar energy?

Answer: Three companies that have done nothing for their shareholders for the combined 40 years that they've been in the public markets. The companies are Microvision (Nasdaq: MVIS), GigaMedia (Nasdaq: GIGM), and Energy Conversion Devices (Nasdaq: ENER). They've been dribbling the ball to nowhere.

If -- with an objective eye -- you course through their business plans, and evaluate their financial statements, I think you'll agree that it's likely that these three businesses will create no aggregate shareholder value over the next 10 years. Sure, they may bounce around from $3 to $6.50 to $2.25 to $8.75 back to $3.25 from year-to-year. And storytellers and speculators will attempt to call the entries and exit points to perfection. Some will make money. Most will lose money. But in the end, these firms will contribute nothing more than background noise to the wild minority of public businesses that create lasting value for their owners.

When I scroll back through the news stories on a company like Energy Conversion Devices, and read glowing praise like this for a company that has burned through cash for 17 years and created no ownership value ... I remember how important it is for long-term investors to read past the fairy tales, ignore the technical analysis, and bear down on the financial realities. You will look upon articles like this one, brimming with enthusiasm when the shares were much higher than today, and click on past.

Doing so will make clear that more than 70% of all public companies out there are not worth your time, your intellectual curiosity, or your capital.

Fool co-founder Tom Gardner and Motley Fool Stock Advisor co-advisor does not own shares of any companies mentioned. The Motley Fool has a disclosure policy.