Well, their bass player, Leonard 'Hub' Hubbard came to mind. One may not know his name, his voice, etc BUT one thing you can never mistake about him is his penchant for smoking what appears to be a cigar. All the time. The man will be playing away on his bass and simultaneously blowing away on that cigar. Before I knew his name, I knew him as the guitar player from The Roots with a cigar always firmly clenched between his lips. For him this has definitely become his signature look because any picture I have seen of him will have him with a cigar, even if it's not lit. He has worked it so that it forms part of his appearance, personality and mien. Here's another look:
I think a signature look is about more than establishing a fashion identity. After all, I believe it is 'the man that maketh the clothes' therefore as much as clothes can accentuate and make you feel good. You should be able to feel good and accentuated without the clothes (pun not intended). For some the signature look is more about accessories than the way they wear their clothes. Woody Allen is synonymous with great and interesting films but he's also almost equally known for his round black framed spectacles. This is unmistakably Woody Allen. When you see him you see those spectacles. And when you see those spectacles or anyone else wearing something of the same kind you definitely think of Woody Allen.
Some signature looks go way back and haven't changed but, instead have transcended time. Enter Dr. Cornel West. With his slightly unkempt afro and full beard. This is Dr. West and nothing can ever change what this look represents to him. It may be religious, personal or cultural but what remains is that he will forever be known for his full body of hair. One can also surmise that the gap in his teeth was deliberately left 'open' so as to incorporate it into his look.
Still on the subject of hair I'd be remiss if I didn't mention Questlove, legendary drummer of The Roots as well. That afro has been his look for the longest time. Why it works is that he seems to love it and therefore owns it as well. The key to a signature look is confidence. Without confidence you're most certainly going to worry about peoples eyes and opinions about it.
Now a signature look only becomes signature if it worn consistently. There might be variation, changes, alterations, transformation, etc, however the foundation of it all should never be lost. Which brings me to my point about sticking with your signature look even if it seems out of place, obsolete or antiquated. After all it is your look.
Maxwell has shed the full body of hair he once possessed and has settled on something shorter and visibly neater. What he has adopted, since he has undergone a transformation, is the soul patch just above the chin. What I have also noticed is his new found love for double breast suits. Now that's a look that'll never go out of style.
Ultimately what I'm saying is, a signature look is about self expression, a point of view and creativity that reflects a comfortable and easy-to-assemble wardrobe. The signature look is founded on knowing what works and looks best on you.
PG: Man to man, generation to generation.