1) The uncomfortable lack of distance between the actor and the characters he plays, manifested by a lack of human dimension (humor, empathy, social restraint);
2) The cult of “infamous personality” that has been built up around Tierney over the years, which Mark references obliquely in his commentary.
The cult-like response to Tierney has produced a theory of noir psychopathy that often doesn’t keep enough distance between fiction and reality, Of course, sensationalizing Tierney in such a way is a cynical ploy to sell seats in movie theaters, and it still works, because film culture has taken the types of extremity “pioneered” by him and pushed it much further.
Tierney did have a somewhat gracious side to his personality, which would display itself occasionally in interviews during the latter part of his life, but it was something that he could sustain for only so long before sociopathy and alcoholism intervened, which would result in yet another notorious incident, such as the one Eddie Muller “celebrates” at his personal web page.
For my money BORN TO KILL is the distillation of the psychopathic character type in noir and is the template for much of what followed. How much of that is Tierney acting, and how much is Tierney being Tierney is virtually impossible to parse. I think Mark’s idea of Tierney in place of Burr in PITFALL is off base, since Tierney projects mere menace and has no form of character coloration to supply, which is what Burr did, often magnificently. As I put it in a reply to Mark’s writeup, Tierney is “all noun and no adjective.”