Betty Lyons smells armpits; the ''odor judge'' is seen sternly sniffing a shirtless man's underarm on the cover of photographer Schiff's ''portraits of unusual occupations.'' Jennifer Kelley is a knife thrower's assistant; she lived to tell the tale after her boss outlined her frame with eight steel hatchets in 30 seconds. Jeffrey Bleim dives for sunken golf balls; at least he makes roughly $60,000 a year for his trouble. They're tough jobs but somebody's got to do them. Schiff's choices can be sophomoric -- see the semen wrangler and the artificial inseminator, the Porta Potti serviceman and the pooper scooper, the male tampon tester and the female men's room attendant -- but she did spend 12 years all over the country compiling this smiley little book. Perhaps hers was the oddest job of all.