Even in his heyday, Errol Flynn hardly had a nice-guy image--what with statutory-rape trials, ugly divorces, and such. Then came My Wicked, Wicked Ways, a pathetic early demise, and confessionals by assorted Flynn women, all adding extra grime to the lurid (though still devilishly macho) persona. And a year ago The Secret Life of Tyrone Power threw in bisexuality too, with gossip of a Power/Flynn affair. So Higham has to work hard to give a sense of freshly shocking dirt, and he does his low-level best. He expands on the Power/Flynn liaison, reports compulsive dalliances with young boys as well as girls (""the result of wanting to be accepted and admired and proven to be a potent male""), records a one-nighter with 18-year-old Truman Capote (""If it hadn't been Errol Flynn, I wouldn't even have remembered it"") and maybe one with. . . Howard Hughes. Also on the psycho-sexual front: brutal rapes (sometimes perhaps fatal), voyeurism (trick mirrors), sadism, kleptomania, exhibitionsim, and a rabid phallic obsession (his home-decoration featured the penis motif). But the relatively big news here is Flynn as Nazi spy--sort of. Flynn has always been known to have been anti-Semitic and vaguely suspect politically, but here Higham makes the most of his long friendship with ""the most amazing personality he would ever meet""--Nazi agent and all-around crook Dr. Hermann Erben (a major source of Higham's material): Flynn is seen using his influence with Eleanor Roosevelt to fend off FBI investigations of Erben; he had a Nazi-singer girlfriend, Nazi friends abounding, and Higham fumes over the FBI's failure to expose Flynn in pre-Pearl Harbor 1941 (as if pro-Nazism were either a rarity or a crime then); but as for actual intelligence-gathering, ""we may never know, but it is likely."" Otherwise, this is the standard star-bio, skimming over the films, rehashing the rape trials, oddly clinging to sentimental, heroic fan-mag vocabulary (""he found his deepest satisfactions in the clean life of the sea"") while wallowing in Flynn foibles. And not even an emphasis on Flynn's fabulous inventory of illnesses (sinusitis, hemorrhoids, heart attacks, tongue cancer, tuberculosis, hepatitis, morphine and cocaine addiction) manages to generate sympathy for this pathological case--a case that Higham makes virtually no attempt to explain or even recognize. Those who still remain attached to the dashing Flynn of yore may want to flip through the dull stretches to the hot stuff here; for non-fans, the condensed highlights (which have already appeared in teasers in People magazine and elsewhere) will easily suffice.