FOR all their extravagance, Ken Russell's films have never lacked exuberance or humor, which makes the flat, joyless tone of Crimes of Passion a surprise. Much of this is attributable to a screenplay by Barry Sandler filled with smutty double-entendres and weighty ironies. Only intermittently does Mr. Russell break through with the kind of manic flamboyance that is so singularly and rudely his own.