I might be a little careful about 'diagnosing' inebriation or other such conditions...
The old line goes that only two classes of people are allowed to say someone is 'drunk': Medical practitioners, because they have been trained to do so, and Police Officers, on the grounds that 'it takes one to know one'.
Although obviously just a funny line, the first part of the statement is true, and is worth knowing when you're commanding a public transport aircraft, because you need one or other type of person to help you if you try to throw someone off for being 'drunk'.
However, whilst in no way condoning flying under the influence, I would opine that the rate of accidents or serious incidents in which crew member inebriation was a factor, is extremely low.