Michael Kun entertains some fairly profound questions in his deft and zany little novel, You Poor Monster, even if he never arrives at any satisfying answers. Ordinary-guy lawyer Hamilton Ashe is awakened one night by a charming, disheveled neighbor requesting a scotch and soda and help with his divorce. This is Sam Shoogey, novelist. Or is it Sam Shoogey, insurance salesman? Or is this epic talker ''He was cheerful, and he was grave, and he moved from one to the other with amphibious ease'' a pathological liar? Kun never quite manages to make you care, but he makes you think: ''The lives of. . .everyone we will ever meet are essentially unknowable. All we can ever know about them are the stories they tell us, and if those stories aren't true, what then? What then?''