The commercial opened on a lone, bearded farmer standing in a dark field. A narrator intoned meaningfully that less than 1 percent of American farmland is organic. But, the female voice continued, we could change that simply by buying Michelob Ultra Pure Gold, the first national, certified-organic beer brand. There was the pop and hiss of a twist-off bottle top, and suddenly we were in the club, only the club was a subway station and a woman carried a six-pack with her onto the train.