Corning (NYSE:GLW) has gotten a bad rap from investors these past few weeks. Those investors should feel ashamed.

Hit by rumblings of a falloff in LCD TV demand out of AU Optronics (NYSE:AUO), LG Display, and Sony (NYSE:SNE), Corning's stock price exhibited a glass jaw this summer. Over the two months since the rumors began flying, Corning has shed nearly 25% of its market cap, knocked back to where it was trading in early 2006.

No hard feelings
You might expect Corning would be upset by the diss. After all, in its most recent earnings report, management continued arguing that things aren't nearly so bad as people think. LCD TV sales were up 30% in the first half, and as supplier of the glass that goes into these sets, Corning expects its own sales to be up 30% by year's end as well.

But rather than resenting its flighty shareholders, Corning defended their interests this week. Yesterday, management warned investors that a Canadian outfit by the name of TRC Capital is trying to get them to sell their shares at below-market prices by way of a "mini tender."

Recipe for fraud
Mini tender. It may sound like the latest menu offering at KFC, but this is no tasty, bite-sized chicken treat. Rather, it's a somewhat devious plan to dupe unwary investors by way of mailing them official-looking documents offering to buy their shares for less than market price. In this case, TRC is offering $20.50 to any Corning shareholder who wishes to part with her shares -- which, as Corning points out, is about 5% less than these same shareholders could get by simply clicking "sell" on their online brokerage account!

But while an obviously dumb trade, TRC's offer is hardly an anomaly. In fact, we've been warning investors about this firm's duplicitous "bargains" for years -- to no avail. They're still in business, as evidenced by the other mini tenders they've run this year for shares in AMD (NYSE:AMD), Boeing (NYSE:BA), ConocoPhillips (NYSE:COP), and Marathon Oil (NYSE:MRO) -- and many more.

Clearly, somebody out there still isn't getting the message. So kudos to Corning for helping to warn the unwary.

Foolish takeaway
As for the rest of us, it's time to wise up -- by which I mean, get more Foolish -- quit falling for mini tenders, and help put an end to these schemes.

Fool contributor Rich Smith owns shares of Boeing. The Motley Fool has a disclosure policy.