I spotted this Competition GS on craigslist last week and pointed it out on the "are you looking for one of these?" thread. The only image in the ad was terrible and it looked like the paint was stripped so I ignored it initially, but found myself in the neighborhood of the pawn shop that was selling it later in the weekend, so I popped in for a look.
The frame had huge peculiar patches of rust on the seat and down tubes, and a smattering of typical rust specks showing through the paint elsewhere, but the chrome and components were very clean. The front derailleur and inner chain ring are gone, and the front wheel is a cheap replacement, but the rest of the original Gran Sport group is intact. I'm going to have a hell of a time finding the chain ring, but the derailleurs are cheap and plentiful.
On closer inspection, I noticed that the rust had what appeared to be brushstrokes, and it covered the decals in some places! Figuring I could use the GS group on my Super Course, I made an unreasonable offer and the seller accepted.
Whatever this brown/red goop is, it's not rust (though there is some of that,) I cleaned it off one side of the seat tube fairly easily with acetone.
It will be interesting to see how well it cleans up, but sadly there are two handlebar dings on the top tube, so this frame will probably end up as a hipster's polo bike.