I am the owner sole pilot of a 2015 RV-12 SLSA with under 100 hours and the pilot seat is filthy and evidently uncleanable after trying about 10 different cleaning agents. I have owned many luxury cars and never had this problem. I am getting ready to try and order a replacement seat cushion and asking for suggestions. No I don't normally fly with dirty shorts!
I would post a photo but don't know how yet.