Hmmm...road salt and/or WD-40? Or maybe just send your Surly's on a road trip into a friend's snowy winter? 
Seriously....my Surly's FFF stickers are almost gone on their own. But I live in the snow belt and the Surly's get most of their riding is in slush. So road salt and, when I'm too tired to give them a good cleaning when I get home a sloppy spray down with WD-40 (yes, yes, environmentally crap, but occassionally I slip) are probably the cause.
But now I know how I can get rid of the "F Fin" sticker that is left on one and the "Fatt" on the other....
2009 Waterford RS-14 S&S Couplers - Brooks B68-Anatomica - Traveller
2008 Waterford RS-33 - Brooks B68-Anatomica - Go Fast
2012 Waterford Commuter - Brooks B68-Anatomica - 3.5-Season/Commuter
2011 Surly Troll - Brooks B68 Imperial - Snow Beast