I use light olive with good succes myself. Maybe Fred is just jinxed with that color?
For some reason, I seem unable to get fish to grab a GP -in any color!. I don't understand it. I use it enough (more out of determination to get one with it) but have only managed a few fish ever with this bug that is held in such high esteem by many steelheaders.
I agree with Rob about the (lack of) semblence between a plug and a sculpin. Who knows why these fish hit? We can hypothesize all we want and we never truly know. Sure, some ideas seem plausible or even probable but we still don't know. The important thing is we know they do, and this builds confidence and, well you know the rest. It's kinda fun to think about the "why" though.
Anyone else got a fly that puts a jinx on them as soon as they tie it on?