Back to living under the flight path, as I do very near a small regional airport with maybe 20 flights a day. The jets do leave a greasy soot on my trees, and we don't get a lot of rain (except this year) so it builds up over time. Fortunately I live on the landing side, so quieter and presumably cleaner.

I don't have much hope the soot will go away. The jets over my house are A320's and 737's, plus a few puddle-jumpers. I can't see them being electrified, and future bio-fuel is probably just as sooty.