It seems that this issue has come up a few times, and has been dealt with on an ad-hoc basis.
It is currently cocktail week, and several users posted questions that (I believe) were in good faith tagged as cocktails, even though they are arguably borderline. These included whisky and water, angostura bitters, and vodka.
On the one hand, I understand that these questions may not strictly be in the "cocktails" category per se, but are not altogether unrelated to the subject of cocktails, and being that they are asked in good faith, I do not want to disqualify them from the contest on that technicality.
So, how should we deal with these sorts of questions during a contest week?
Techniques, equipment and ingredients used in preparing and serving mixed alcoholic drinks, as well as non-alcoholic substitutes ("mocktails").
. While there is certainly still room for 'border cases' I think your examples for cocktails fit well into this description.