How'd that nasty soot get in MY trunK?

[morgantruce]

Well, OK... it might have something to do with that rear muffler that has a hole in the back--I know I need to replace that. The engine does not run particularly smokey at all.... but of course it's making some soot being a diesel.

There are two thumb-sized water drains on either side (under the side liners) that have a series of flaps in a small circle---that seem designed to let water drain out--and keep big snakes from crawling in. Under the spare tire, there is a round hole about the size of a half dollar that is wide open.... I figure some kind of plug is missing from there. Since the spare tire is especially sooty, I figure this hole is quite the culprit. There's a panel over the tire... and a piece of carpeting over the panel that looks like its spent a decade at the EXIT of a coal mine---near a sign reading: "All Miners Please Wipe Their Boots Before Leaving!"

There's enough soot in the trunk that I wouldn't think of putting any luggage (or white wedding gowns) back there. This is a new (27 year old used) car to me... so I dont know if I just cleaned out a month's worth of soot----or 27 years worth of soot.

Which are the usual suspects (after replacing the muffler)?