So I just checked out a used bike I'm contemplating buying and I opened up the gas tank and it looked like someone dumped paint in it. The owner claimed that's how its been since he's had it. I took a picture...is this some kind of rust "band-aid" or something? It looks like there are little bits of rust in there.
It lloks like someone coated the tank to seal the rust. If its not chipping or swelling or generally crappy loking it should be OK.
If you buy it and still worried, you could always remove the tank, remove fuel pump and flush the inside with some new gas. Try to place the old gas in a container where you can see if the flakes got poured out also. rich