I looked at a used 2002 VROD today. I noted there was a black fluffy residue at the mating surface/gasket of the rear cylinder a few inches below the finned area. The thickness varied but it ran for several inches along the gasket on the left side of the cylinder.

I'm guessing this is a red flag?

 

Just a VROD trying to mark it's territory!

 

Bro. it's probably just an exhaust leak. As long as it's not oil. If it's powdery it is exhaust.