There's another version of the Authenticity Policeman called the Half-Knowledgeable Commentator. (I note this person sidling sideways into some of the posts above).

I have an instructional blues video on the Tube, demonstrating some very old, entirely unoriginal and simple blues licks in A. I've now lost count of the times this comment and my increasingly frustrated answer have appeared:

Comment: You got that from Eric Clapton's "Change The world."
My reply: No - it's a very old blues riff used by many people, including EC.

Comment: This sounds like Eric Clapton's "Change The world"
My reply: It's an old blues riff that's been used by many blues players.

And then a little later...you can guess the rest. So let's hear it for the H-KC!