Real estate has resale value, and a market against which value can be measured.

Where is the resale value of breast fondling? Who's to say that the woman charged too much to have an old man fondling her? You? Who's to say the man did not get his money's worth? Would any old breast do?

If he's medically diagnosed, then the time to claim he's incompetent to handle is own affairs is before the transaction, not after, imho -- especially when you have such an unquantifiable value as the fondling of the breasts of one particular woman.