OOOh I like the look of Elbow Grease...it's just coated with contaminants, probably mostly oil and grease.
Does anyone know what the seat material is? It's a bit rubbery or maybe a vinyl?

Zeus: luckily no paint on mine...you could try some acetone (WARNING: given I don't even know what the seat is made of please check before using acetone in a small non-visible area!)