From last two posts I take it they have not done much laundry in their lifes especially with sex stained clothes. Some stains stay even after you wash the clothes. There is a nice market out there of products to help prevent this either prewash or some postwash. Fact is clothes can be clean and still have a stain.
As far as the OPs fetish, that is hot. I know I have stained a few outfits and I am sure they wore them later for other guys.
Alpha-Omega
CEO and Founder of PETT (People for Ethical Treatment of Trolls)
Creater of the Faptastic Four
