MBIA (NYSE: MBI) executives recently slashed in half the price they will be paying for shares in the company's recapitalization, but bullish observers are still pointing to their token investments as signs of confidence in the company's future.

The Wall Street Journal's Inside Track column (subscription required) gives investors good reason to be skeptical of these deals -- which appear to me to be little more than publicity stunts where the investments made by executives represent a pittance compared to the compensation they have extracted from the company's shareholders in spite of scandalously horrendous performance.

Here's the thing: Jim Cramer has said frequently that insider selling happens all the time for many different reasons, but insiders buy for only one reason: they think their stock is going higher.

Maybe that was true at one time but as more investors have recognized it, it's become less true. That's because struggling executives who are on a well-deserved hot seat know that insider buying can send a message to investors that they believe in the company, have a stake in it, and should be given a chance to right the ship. But in cases where the investment does not represent a significant chunk of the executive's net worth, it's little more than a photo-op. Shares of Sharper Image soared more than 40% on similar token insider buying -- a run-up that I blasted as irrational at the time -- only to plunge into bankruptcy a few months later. Investors who followed the wisdom of "follow the insiders" lost more than 90% on that charade.

If you're going to use insider buying as a predictor of future performance -- a notion that I'm not completely sold on -- look for sustained buying in quantities that represent a meaningful chunk of the executives' compensation. Don't fall for window dressing.