Danny
You are using holier than thou as some sort of insult. I've sat in pubs and drunk alcohol-free beer. It's not that difficult. There are hoards of people reading PPRuNE who would die for the honour of being a commercial pilot. So don't tell me I'm some sort of pathetic individual if I say pilots should absolutely be alcohol-free when they fly. What's the point in banging on about safety if you then willfully degrade your own performance. As yet nobody has countered my point that half a pint of beer has measurable adverse effects on pilot performance. Underlying this discussion is the feeling that lot of people have - that being slightly under the influence is neither here nor there and just part of life's rich tapestry. I'm not holier than anyone else. I'm just not self-deluded.
Issues of fatigue and legal jurisdiction are red herrings. The question is should an ordinary professional pilot believe in being sober, or indeed, should he obey his airline's rules?
As for spurious readings, I doubt this can happen but more to the point I would lay money that the pilot concerned had acted inadvisably. It's extremely unlikely this sequence of events would have occurred following a mouthwash. In fact I'd wager he'll turn out to be rather more than the 0.2 figure.