What's the issue with yellow slip? All it does is give you a trip over other people on reserve. They will assign it from junior to senior unless the senior guy on reserve yellow slips it. It would never stop a GS or WS, the trip in question will go out to a reserve anyway. I hardly ever YS but if I know I'm going to have to fly anyway I will pick the better trip. Please explain why this is a bad thing?

Out of base WS usually gets in the way of GS. And what's with the dude that WS when the last ten trips assigned were GS. To me that is way worse than getting a better trip or flying instead of sitting around the crash pad instead of a junior guy on reserve who lives local.