Chris, I feel your pain. I have had my fair share of lenses 'in good condition', that have:
  • had fungus (granted, one ebay seller gave me the whole purchase price back, but that was the only one).
  • Sticky aperture blades - I have fixed most of them myself, but it's always a fiddly job
  • one didn't fire the flash (Bronica SQAi) - I didn't find out until around 6 months after buying it

I suppose this is the joys of buying second hand. But, with the way that ebay prices have gone of late, I have given up on it and will buy further gear from known sellers on here (or LFF), KEH or FFordes.