I simply must quote again from Bradford Dillman's IMDb biography, which states that he "possessed charming and confidant good looks that were slightly tainted by his bent smile, darting glance and edgy countenance that often provoked suspicion."
The evil smile.
Even when Bradford played non-evil roles, one could never fully trust him. All he had to do was smile...
Many actors have a defining characteristic, something that is uniquely "them". This characteristic can be both integral to the actor's image...and difficult for the actor to overcome. For instance, Marilyn Monroe found it difficult for anyone to think of her in any way but as a "dumb blonde". For Bradford-- it's difficult to think of him as anything but an evil genius.
And that's because he always played such brilliantly evil genius'.
And that's also why one can never trust him as a non-evil genius. He played quite a few non-evil roles, but you never know for sure that he's not evil until the end of the movie/TV show. With Bradford, you always want to give him the benefit-of-the-doubt that he IS thoroughly and completely evil and probably runs over old ladies with his car for fun.
When Bradford plays a "conflicted character" it usually means there's a small, odd part of him that wants to do the right thing.
Okay, anyways (I could keep on making up these examples all day long! ;-D)...
Bradford Dillman really did have THE greatest evil smile ever. He played many different types of villains: those DRIVEN to villainy by circumstances, cold and calculating villains, desperate villains-- whatever. But, his awesomest roles of villainy were his gleeful, over-the-top, brilliantly evil, genius villains. Those villains smiled because they simply liked being evil!
And that's why it's difficult to let Bradford be non-evil. Because you can't tell. What is there to distinguish from Bradford's "I'm a nice guy" smile and his "I'm currently pumping toxic waste into the drinking water of several major U.S. cities" smile? Nothing.
And THAT is exactly why he is so stupendously amazingly cool. He's brilliant and can play any role. But, he NEVER plays a role stereotypically. He never plays an ordinary straight-forward anything. He can't play an ordinary old nice guy anymore than he can play an ordinary old bad guy. All of his performances are complex and unique.
With every one of his good guy's, his smile betrays a hidden inner core - perhaps an evil inner core. And with every bad guy his smile hints that there's something more behind the facade, maybe a nice guy? (More than likely it's just a deeper and more awesome evil streak. BUT STILL. ;-D)
Anyway. I am a big fan of Bradford Dillman and especially his seriously cool evil smile.