cleaning soot from inside exhaust

When I start my truck little black flakes come out of my exhaust. Like black snowflakes. I was told by my mechanic that I need to clean out the pipes, like a chimney sweeper of old. Ive racked my brain on what I would use for that sweeping. Only thing I could think of was getting a ceiling fan blade cleaner and bend the bristles into a round shape. Any advice?

Plus: are these flakes an indicator of an engine issue? 1991 379, 3406b engine.

 

Ridgeline: Good point. He told me that the heat and pressure would send most of the soot to the exit of the exhaust. Makes sense.

Roger McG: He didnt say it was necessary to clean them out. Just thought it should be something I do as general maintenance. Plus I wasnt sure if the flakes were a sign of something wrong.

Personally, I dont like the black crap on my stacks or top of my sleeper.

 

I am being serious. I always liked the look and tinging sound of the caps as I grew up. I do plan on getting the caps when I cut the stacks a little shorter. It looks like King Kong took a horrendous dump on top of my sleeper (black soot running down sides when wet).