Bit dull this one, but I'm curious to know how everyone 'manages' their baking trays. I buy them all shiny and non stick, I wash them after every use of course but over a year or two they become blackened and grim no matter how hard I scrub them. If I try to clean off the worst of the black stuff with oven mate or something it takes off all the non-stick coating which means I end up with blackened non stick trays that I have to coat with baking paper/tin foil. Is there some magic baking tray cleaning thingy I'm missing?