Brian Legge
Veteran
From the photos (yours and the buyers), I'd view this as a miscommunication about the state of the lens or different definitions about 'clean'.
Most older lenses - particularly those which haven't had a recent and thorough CLA - will show all sorts of debris when shining a flashlight through against a dark background. None of it would show up in photos like the ones you took, looking through the lens against a white background.
At least personally, give the buyer the benefit of doubt and assume they thought the lens would be cleaner than it was. I don't see any intentional mistruths on either side here. Neither of you have a reason to compromise.
If I were in your place, I'd stick with the 'send it back for a full refund' offer and let them decide what to do. They can either keep it as is, take your offer or file a paypal claim (which will likely result in them sending it back for a refund - exactly as you offered).
Most older lenses - particularly those which haven't had a recent and thorough CLA - will show all sorts of debris when shining a flashlight through against a dark background. None of it would show up in photos like the ones you took, looking through the lens against a white background.
At least personally, give the buyer the benefit of doubt and assume they thought the lens would be cleaner than it was. I don't see any intentional mistruths on either side here. Neither of you have a reason to compromise.
If I were in your place, I'd stick with the 'send it back for a full refund' offer and let them decide what to do. They can either keep it as is, take your offer or file a paypal claim (which will likely result in them sending it back for a refund - exactly as you offered).