Very interesting question but strictly speaking as its a buisness encounter and entered into as such by both and if the escort provided that condom for the purposes of supplying said buisness service then really she has provided her customer with an inferior or substandard integral piece of equipment and not the customers fault unless it can be proved his actions caused it to fail.
It would be like a plumber causing your house to be flooded by using substandard parts and then suing for the costs to repair your own house... The client should stictly speaking pay nothing..
Just looking at it from a total buisness pov.