Notoriously difficult question. And one so rarely has the proper time to formulate a proper answer to it.
Anyone who, in the pale moonlight, would present him or herself as the Devil must be called into question. I can't imagine the Devil would present itself as such openly and notoriously to someone who isn't a blues musician looking for mastery. Then again I can see how an individual might be so savvy as to warrant the lack of subterfuge. Does the Devil always lead, I wonder? Perhaps sometimes he follows to put one at ease. Part of the disguise.
I myself have danced with one who was introduced as the devil but wasn't. Possibly some who were really the devil in disguise.
Actually a couple of times with persons bearing the name Lucifer. I shit you not. Whether or not bearing that name makes one The Devil is hardly clear cut though
So the question is in doubt. I do know what Jack Nickelson said when he was asked this question by a fan who happened to be at the urinal next to him.
"I have now, baby."
It is not meet for you or I to question the wisdom of Jack