I remember an event here in the 1970s, where a local chap was breathalysed and passed, with quite a low amount registering - when the copper gave him the good news, he was absolutely livid - "As a life-long temperance campaigner, I can assure you that no alcohol has ever passed my lips!"
He was not at all happy at the perceived slur on his character and a cursory investigation took place, to see it the device was faulty or there was some other reason.
It turned out that the orange juice in his fridge had been there for quite a while and had fermented to a small extent, producing a rather weak Cointreau substitute that he was innocently imbibing...