The first thing that spotted mine was simple raindrops. I used what I had around, which was a can of that spray upholstery stuff with the plastic scrubber top. When I did that, the cleaned area still looked different than the untouched area, which led me to scrub the entire seat. It still doesn't look right. Next I'm trying a mixture of mild soapy water. I haven't decided yet to use dish detergent or laundry detergent. Is there a commercial product that would be better or should I just stick with the mild soapy water?