DAVE BARRY DOES JAPAN by Dave Barry (Random House: $18; 212 pp.) Now here's a job any working writer might covet: Take a trip to a place that's always interested you. Bring the family. Stay three weeks. Come back and write about what you did. And oh yeah. The publisher will pick up the tab. First class. Nice work if you can get it--but you probably can't, since Dave Barry has staked out the turf. The one really useful piece of equipment he brings along is his singularly demented brain, which he trains on the island nation of Japan with all the delicacy of a blowtorch. If anyone else said half the things Barry says, or even thought them, would we vote for him for dogcatcher? Nothing is sacred. He takes on the Japanese language, including cryptic souvenir T-shirts, and comedians, and sexual preferences. He goes after hotel clerks for being too servile, then turns around and gooses stateside service personnel for being oh, less than competent. Which is probably how we can get away with his particular brand of outrage (if he does; if I were he, I'd watch out for hostile-looking people who, as he says, suffer from a certain "lack of height"). He dishes in both directions at once. Barry is not the ugly American, making fun of foreigners. He's an equal-opportunity humorist. Nobody, on either side of the Pacific, is safe.