I can't be the only one thinking that the once-breakthrough CBS (NYSE:CBS) hit Survivor is running out of immunity idols. The island-based reality show has been getting slugged around by the media lately, mostly as a result of the show's decision to initially segregate the fall season's contestants by race.

Now it seems as if the CBS sponsors are snuffing their own torches. According to the new issue of TV Week, General Motors (NYSE:GM) has decided to back out as an advertiser when Survivor: Cook Islands debuts next month.

TV Week spoke to a GM spokesman who explained that the decision was made several months ago. Advertising on a show that revolves around primitive living on a barren island was a tough tie-in to GM's automobiles.

I don't buy it. For starters, GM has been able to blend in nicely into the show in the past. GM cars have made ideal challenge rewards in the past. Ever since Colby Donaldson won a Pontiac Aztek during the second season, a GM car has been the beefiest prize leading up to the final tribal council.

GM's car giveaways have even fueled the Survivor Car Curse theory; no contestant has ever won the car challenge and gone on to win the million-dollar purse at the end. So let's not let GM skate that easy. Companies don't advertise on Survivor because they want to reach out to camera-hungry backstabbing show contestants. They do it to reach a stateside audience that will get up the next day and drive to work.

The timing of the announcement is also suspicious. Yesterday, GM announced that more than 2 million of its 2007 model cars will roll out with OnStar Turn-by-Turn Navigation. A GPS service for those lost and in need of directions? Tell me that's not a feature just begging for a photo-op within a Survivor challenge or two.

The one thing we do know is that if the negative fallout over the show's segregating ways also turns viewers away, the reality show's run will likely be near an end, and GM's exit won't spell opportunity for rivals like Ford (NYSE:F) or DaimlerChrysler (NYSE:DCX) to roll in as replacements.

The ratings have spoken.

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Longtime Fool contributor Rick Munarriz has never submitted a zany audition tape to Survivor, though he'll embarrassingly admit to once being lured to a Weakest Link open audition. He does not own shares in any of the companies mentioned in this story. He is also part of theRule Breakersnewsletter research team, seeking out tomorrow's ultimate growth stocks a day early. The Foolhas a disclosure policy.