4potflyer sums it up nicely.
It's been well discussed...even here in PPRuNe...that there are various circumstances that can produce an apparent smell of alcohol on the breath when no drinking is involved. Mouthwash, as frequently mentioned, is one of them but there's also the classic case of a particular diet that gave an unfortunate pilot bad, apparently alcoholic, breath.
It's just as wrong to assume the original accusation was malicious as it is to assume the innocent pilot was guilty before seeing the results of the blood test. Unless the full facts are known, this sort of speculation is just as damaging as that rubbish on the AOL board.
Bobbsy