For generations, marketers have used gay themes in TV ads for cheap punch lines. But today, the joke is on any corporation that alienates a group that spends about $452 billion annually. That's why dozens of companies, from Miller Brewing to Hewlett-Packard, are turning to Commercial Closet Association founder Michael Wilke. His presentation explains how certain portrayals are perceived by gay people. Like, say, a 1996 T.J. Maxx ad in which an ultrafeminine man throws a hissy fit. The ad ends with him at a piano playing the notes F-A-G. Wilke warns about "positioning homosexuality as a perceived 'threat' for humor." (Effeminate stereotypes are OK if there's some other element to the ad's humor.) Madison Avenue is taking notice of the market. A 7Up ad this year using prison-rape jokes was pulled after a flurry of complaints, including Wilke's thumbs down. And Subaru is now so aware of its lesbian following that tennis icon Martina Navratilova, scorned by marketers in her '80s heyday because she was openly gay, is now a pitchwoman. The CommercialCloset.org site, which gets about 100,000 unique visitors a month, features Wilke's analysis on more than 1,000 viewable ads. "Big companies don't want to offend," says Wilke. "That's basically the opposite of the point of advertising."