Hmmm.. interesting, pardon me if i'm wrong.. i've no knowledge of how 'aviation related' personel are "tested" for alcohol..
But, the standard UK police practice is for the accused to be tested roadside with a handheld device which on it's own is NOT enough to bring a successful prosecution as it is not accurate enough.
Any charge is as a result of using an evidential breathaliser at the nick - these work on analysing the breath from deep within the lungs and therefore should be 'immune' from contamination from instances such as alcohol wipes or residue coming in contact with the mouth...
However.. (if your driving/flying) i'd strongly advise against using any mouthwashes - these usually contain rather alarmingly large amounts of alcohol
In any instance, i'd imagine the accused would be offered the chance of a blood test which would prove their innocence?