Correction:

It is raining here today and my passenger floor got wet. However, the trickle I described above is/was not the source of the flooding. Instead, the drain in the fender just in front of the passenger door was clogged, and water accumulating in the small reservoir at the bottom of the fender was backing up through a wire/cable opening, and into the passenger floor.

If you suspect this is your problem, feel around for a cone-shaped, rubber nipple under the fender, just ahead of the passenger door, then stick your finger up into it and clear any blockage.

For almost two years I wondered what the slow dripping from that area was after washing the car, or after it rained. It would persist for hours. After clearing the blockage, the water ran out like a faucet. Luckily, the bottom carpet with the foam padding was out of the car, otherwise it would take another three days to dry it out.

FYI: Since the wet under-carpet has been out of the car, the interior no longer smells like "breath" in wet/humid weather.

__________________
2008 E350 4matic / Black/Anthracite

------------------------------------
Gone but not Forgotten:
2001 E430 4matic, 206,xxx miles, Black/Charcoal
1995 E320, 252,xxx miles, Black/Grey
1989 260E, 223,00 miles, Black/Black