(FORTUNE Magazine) – Will the Simpsons be as big again this year? No way. The hot tickets in 1991: Texas, country music, white rapper Vanilla Ice, and, yes, tattoos (girls included). So says New Yorker Irma Zandl, 41, who earns her keep by predicting the ephemeral likes and dislikes of America's adolescents. Nestle, Procter & Gamble, and PepsiCo are among those who pay $10,000 for Zandl's seminars or hire her to help with marketing campaigns and new-product launches. ''She's taken a segment and nailed it,'' says P&G brand manager Brian Sroub. To get beyond traditional market research, Zandl regularly checks out clubs, concerts, and boutiques -- and even visits teens at home. Says she: ''That's how you find things before they show up in the data.'' Her four-year-old consulting firm, Xtreme, was among the first to tip clients to the marketing potential of rap music. One slip: She was slow to glom onto the current Sixties rage. Zandl's latest advice: Don't assume all kids are rebels. ''A lot of kids don't want cool -- they want to be reassured,'' she says. ''Present, say, a deodorant as cool, and they may just think it doesn't work.'' Observes P&G's Sroub: ''What teenagers are thinking is not always what you think they're thinking.'' As any parent can testify.