Just a few days after General Motors (NYSE: GM) broke the news that it was ending its endorsement deal with Tiger Woods, NBA phenom LeBron James' agent told reporters that Microsoft (NASDAQ: MSFT) would not be renewing its two-year old marketing deal with the Cleveland Cavaliers forward.

King James, as he is known, appeared in commercials for the Windows Vista operating system, but very little else came of the partnership. According to The Associated Press, "The partnership faltered when Microsoft executive Joanne Bradford, who struck the deal with James, resigned as head of the company's media network this year."

These celebrity endorsement deals attract little attention from investors when times are good, but with most companies faltering now, they seem to be attracting more ire. James' seven-year, $90 million deal with Nike (NYSE: NKE) makes sense: LeBron James is a powerful force in selling basketball shoes. The terms of the Microsoft deal were not disclosed, but it seems unlikely that James contributed to any increase in sales of Microsoft products -- would anyone choose their operating system based on a basketball player in a commercial?

I can't help but question the motives behind these kinds of endorsement deals: are they inspired by a desire to drive sales and create shareholder value or a desire to hobnob with celebrities?