Washing probably removed most of the capacitor goo (water based I would think), if not some alcohol and a q-tip will get rid of what is left (not rubbing alcohol since that is only 70% alcohol and some other junk).

Discoloration while bad is not the end of the world as long as the trace is still intact and not etched too badly where it will become a hot spot and fail. Even then you might be able to bridge a broken trace with a wire jumper. Generally I keep a multi meter around to check if there is a broken trace.