CalgaryLumina,
Your damp stuff could just be accumulated moisture and dirt over time. It could be a very slow leaky heater core, or possibly a very slow leaky evap core. An oily substance could leak from the AC system, but in short order your AC wouldn't turn on because of low pressure (a leak). I would just disinfect/clean off all parts and then run the vehicle and observe for leaks. The evap core should normally drip condensation water after a while depending on weather & humidity. Thats why the drain tube going through the fire wall. Make sure the drain tube is connected, intact, unclogged, and then the tube must make a 90-degree turn downward after going through the firewall. I had to temporarily disconnect mine when cleaning the evap core. It was difficult to reconnect (took 2 beers and some cursing) and it must aim down when done.
I opted not to buy and spray the evap cleaner beacause I was afraid it would clog up the evap core even more with the very limited access I had. I feel I was able to get more dry fuzz to brush off and fall to the floor this way. I did not think I would be able to get the cleaner/foam and dirt off once applied. It appears a good product but, I think in the case of this car- the evap core almost needs to be disconnected and removed to use it properly. Perhaps wear a mask if you have weak-lung syndrome.