TV host and comedian David Letterman once introduced a sanded plank of cedarwood as Bo Derek's acting coach. Few, if any, critics have disagreed on the quality of her performances, but the greater problem has been the quality of her films. This blond, pale-eyed sex symbol shot to stardom in the title role of Blake Edwards' 10 (1979), as the "perfect" beauty who's the focus of Dudley Moore's comic obsession. Years earlier, an agent had brought the teenaged girl to actor/director John Derek's attention. He immediately put her in his film Fantasies (shot in 1973), which was not released until the actress-now Mrs. John Derek-was a star, in 1981. (She'd also had a small part in 1977's Orca With the exception of A Change of Seasons (1980), which opened with footage of the wellendowed beauty bouncing up and down in a hot tub, most of her remaining films have been directed by her husband-Tarzan, the Ape Man (1981), Bolero (1984), and Ghosts Can't Do It (1990)-and all have been virtually unwatchable. Recent non-John films include Hot Chocolate (1992), the telefilm Shattered Image Woman of Desire (both 1994), and Tommy Boy (1995).