Just as Neji mastered the kaiten w/o having been taught, Lee does drunken boxing.
Not all moves have to be taught.
If Lee has never had alcohol before then he doesn't/isn't expected to know the taste.
EDIT: As to why Lee can't recognize the taste of alcohol, that's only something we can guess about, to get a real answer you'd have to consult Kishimoto.
Who knows even he might not know, could simply be a plot hole that was overlooked.