Are stars good for the environment?

Leo and this star drive hybrid cars. This star promotes electric cars. This one promotes biofuels. According to Green wave surges onto pop culture's shores, "Environmental causes championed by scientists and watchdog groups are reaching wider audiences as they gain prominence in popular mainstream media."

Is all this star attention good for environmental issues? Or does all this star treatment lead to a backlash? I know for certain that there has been much backlash against the Toyota Prius because of its connection to Hollywood. Still, is star endorsement good for the environment, bad for the environment, or does it simply make no difference?