But backstage, he had some global warnings, if you will. For one, don't you dare ask the pretty boy about Jessica Simpson.
"I'm going to practice some conversation conservation right now and try to minimize my bull$h!t footprint," a coy Mayer quipped to a reporter who asked if he still spoke to Simpson.
Also, don't ask him if he has any "eco-sins" (as many of Live Earth's electricity-using, private-jet-flying rockers readily confessed to). We've seen him pumping gas, but it's not clear whether he drives a Hummer (or simply receives them from hot girls). Anyway.
"What is my eco-sin?" John Mayer asked.
"I don't know if that is that provocative a question for me. I don't know. I'm still trying to figure out what my motivation is, what is the positive side to the things that I could do?"
Huh? He later added: "If you want to peg me as not being entirely eco-friendly, you'll win. We have a tour, which is inherently carpooling."
We can only conclude from his remarks that John Mayer is...
- A total loser.
- Both #1 and #2.
Still, he didn't get pulled over with a small cartel of drugs in the car, like Al Gore III - son of Live Earth creator and former Vice President of the United States Al Gore - so there's something to be said for that.
Less confrontational was Kelly Clarkson, who says that while she recycles and carpools, she's still learning the best ways to conserve resources.
"We need just as much information as the audience," she said. "We're not brilliant. I'm not the most educated on the process, but I'm learning."
It's the kind of reply we're accustomed to from the American Idol star, and the honesty (even at her own expense) that we've come to love.
Meanwhile, Rosario Dawson said backstage that not only is she "that person who turns off the light every time I walk out of a room," but that she'd seriously question dating anybody who isn't green.
"I'd probably have a really huge problem with that," she said.
While all these stars are doing their part to help the environment, rumor has it that Britney Spears is simultaneously leading the anti-conservation movem ent.
After all, the lights are on, but there is definitely nobody home up in that piece.