Haven't seen anything about something I found a little while back. I'm just getting around to taking pics and getting the word out.
Open your drivers door (and passenger too) and look forward below the lower hinge. You will see a flat rubber cover on the body side. I enclosed a few pictures. Pull the cover towards you and you will find a ton of leaves and crap behind there.
I park my truck under a tree a lot of the times and constantly pull leaves out of the gutter where the wipers are and even open the hood to clean them out of the vent area but that eveidently not enough. A lot of stuff accumulates in there.
Note: it appears that the mudflaps are the back wall of this crevis area. So I would guess if you remove your mudflaps it is a great place for stuff to get in from the front.