(Mental Floss) -- A good pitchman can boost any product's name recognition with some high-quality shilling. A bad one, on the other hand, can quickly ruin the brand images that companies spend years and millions carefully honing.
Madonna performs at the 1989 MTV Music Awards. She was fired as Pepsi's spokesman that year.
Take for instance these guys and gals, each of whom was given their walking papers following a scandal, public embarrassment, or bout of outspokenness.
Pepsi and Madonna
Although she's back in the news now for allegedly bewitching Yankees star Alex Rodriguez, it's sometimes hard to remember that Madonna was a sex symbol, not just a cautionary tale about taking your Anglophilia several steps too far.
Back in 1989, though, she was not just the embodiment of sexuality; she was also willing to do almost anything to be shocking.
Pepsi apparently neglected to think about the possibility that something could go horribly awry when they took the singer on as their new voice, though.
The soda company signed Madonna to a $5 million deal to make commercials, including one that would include the song "Like a Prayer." That's when the trouble started. The music video for "Like a Prayer" was almost laughable in its willingness to go over the top to appall; each scene of Madonna's religious subplot seems to raise the bar for nonsensical shock value a little bit higher.
Think Madonna getting physical with a saint is offensive? Just wait ten more seconds; by then she'll have developed stigmata! The video caused such a stir that it was banned in some countries, and Pepsi quickly had to drop its Madonna spots and cancel future appearances by the singer. Mental Floss: Where are they now?
Pepsi and Ludacris
In 2002, rap star Ludacris was minding his own business and endorsing Pepsi.
Suddenly, the normally reserved conservative commentator Bill O'Reilly launched an offensive against both the soda maker and the rapper. O'Reilly was incensed by Ludacris' lyrics that glorified drinking, drugs, violence, and disrespect towards women.
He called for a boycott of Pepsi products until the man O'Reilly decried as a "thug rapper" was shown to the pitchman door.
Pepsi quickly dumped Ludacris, and the rapper made quite a bit of hay out of his feud with O'Reilly on several subsequent records, including the jab "Hi Mr. O'Reilly/Hope all is well, kiss the plaintiff and the wifey," a pointed dig at a sexual harassment lawsuit that was pending against the talking head. Mental Floss: The celebrity endorsement quiz
Dell and The Dell Dude
Dude, remember those fantastically annoying "Dude, You're Getting a Dell!" ads from a few years ago?
What you may not remember is that the hyper-enthusiastic "Dell Dude" (actor Ben Curtis) got busted for attempting to buy a bag of marijuana in New York City.
Although the bag of pot was tiny enough that Curtis escaped any big legal entanglements, Dell was less than amused. The computer giant dropped Curtis and his ad campaign shortly after the arrest.
For his part, Curtis has bounced back, though.
He has appeared in off-Broadway productions, and in November 2007 was the subject of a New York Magazine story about his employment in a Mexican restaurant in the city.
Florida State Citrus Commission and Burt Reynolds
The mustachioed Reynolds may not have maintained the star power he had during his 1970s heyday, but he was still an effective pitchman well into the 1990s.
As a former Florida State University football star, it was only natural that he'd find his way into a position promoting orange juice for the Florida State Citrus Commission.
In 1993, though, Reynolds' marriage to actress Loni Anderson had started to unravel, and as the sordid, bitter details of the rift began to surface, the orange juice biz became too wholesome for the man who'd been the Bandit.
The commission phased out Reynolds' commercials, and one featuring Anderson's hand reaching for a glass of juice fell out of play entirely.
Slim-Fast and Whoopi Goldberg
Goldberg would seem like the perfect person to pitch a product.
She's warm, funny, and generally beloved. She's also fairly politically active, though, and that came back to bite her while she was a celebrity endorser for Slim-Fast.
When Goldberg appeared at a fundraiser for John Kerry during the 2004 presidential race, she took the stage waving a wine bottle and firing off barrages of sexual puns based on President Bush's name.
While the audience was amused, conservatives weren't.
Calls for boycotts of Slim-Fast products (sensible dinners were still allowed) started bubbling up among conservatives, and the company canned Goldberg just eight months into her tenure as their spokesperson.
Goldberg remained unrepentant after her firing, though, commenting, "I only wish that the Republican re-election committee would spend as much time working on the economy as they seem to be spending trying to harm my pocketbook." Mental Floss: A brief history of celebrity political endorsements
Pfizer and Robert Jarvik
When Pfizer needed someone to endorse its drug Lipitor, Robert Jarvik seemed like an ideal fit.
After all, who better to talk about a heart drug than the celebrity inventor who helped perfect the artificial heart?
Pfizer started airing spots featuring Jarvik in 2006. In the ads, Jarvik would offer viewers advice about why they should use Lipitor in addition to doing cardio-heavy activities like rowing.
After a few months, though, observers started to notice something was amiss.
Although Jarvik had been to medical school, he never went through a residency or received a license to practice medicine. As such, he shouldn't have been dispensing medical advice to anyone, much less to TV audiences of millions.
The ads drew further scrutiny when it came out that the scenes of "Jarvik" rowing across a lake weren't actually the "doctor" at all, but a stunt double.
Earlier this year, the criticism of the misleading ads spread to Congress, and when the House Committee on Energy and Commerce started investigating the ads, Pfizer pulled the spots and dumped Jarvik to the curb on February 25.
Verizon and Akon
If Ludacris was a victim of Bill O'Reilly, fellow hip-hop star Akon lost his endorsement deal with Verizon as the result of some really questionable decision-making and some bad luck.
While playing an 18-and-over show in Trinidad in 2007, Akon danced on stage and simulated sex with the winner of a dance contest.
One slight hitch, though: club management apparently wasn't great at checking driver's licenses, so the woman Akon got nasty with was actually a 15-year-old girl.
A racy video clip of the event became a YouTube sensation, and Verizon quickly gave Akon the heave-ho, dropping his deal, pulling his ringtone clips, and backing out of sponsoring a tour in which he was opening for Gwen Stefani.
The singer apologized profusely both in the media and in song, but the damage was already done to his career as a phone shill.
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