(MONEY Magazine) – STAR POWER? Celebrities crusading against evil conglomerates are nothing new. But are they effective? Chances are, Chevy Chase's invective against genetically engineered foods at Kraft's annual meeting in April had little impact on the company's practices. Here's MONEY's report card of famous folk and their gripes with big business.

PINK VS. PETCO Ms. Missundaztood wrote the company last August claiming that it mistreats the pets it sells. Grade: Pink gets a D. Petco says the pop star did not respond to efforts to contact her. Must be a Missundaztanding.

LEONARDO DICAPRIO VS. PHILIP ANSCHUTZ DiCaprio slammed the billionaire's efforts to drill for oil on historic Native American ground in Montana. Grade: C. Anschutz bailed out last summer, but isn't it ironic that environmentalists similarly blame Leo's 2000 flick, The Beach, for ruining the ecosystem of Thailand's pristine Phi Phi Islands?

HOMER SIMPSON VS. DUFF BEER Homer staged a hunger strike to prevent Duff from moving his beloved baseball team, the Springfield Isotopes, to Albuquerque. Grade: A. The team stayed put--but now there really is an Albuquerque minor league team called the Isotopes. (No, they don't sell Duff.) --JONAH FREEDMAN