What could a phrase like アルコールはダメなんだ possibly mean?

Question

The phrase アルコールはダメなんだ is from a manga I read, in which a guy responds to his friend when being asked if he wants a beer. He appears not to be into alcohol, even goes so far to say that "I don't like the taste, nor is there any occasion for me to drink".

I'm not sure what possible meanings that phrase could have though. Literally, it'd be "Alcohol is not good", and it could be reasonably thought of as "Alcohol isn't good for your health" (in which case he might be advising his friend not to drink).

I'm curious whether there's a possibility for it to mean "I'm not good with alcohol" > "I can't drink". After all, this seems to be an example of the various ambiguous uses of "wa", in which the topic isn't necessarily grammatically tied to the modifying phrase that follows.

Answer 1

It means "I'm not good with alcohol" or "I don't like alcohol". Of course it can also mean "Alcohol is not good (for your health)" and "Alcohol is prohibited (in this event)", depending on the context. In general, ～がダメだ can mean "to be not good at ～" or "not to like ～". For example you can say サッカーはダメです, 彼は英語がダメです, etc.

Answer 2

If I hear you say アルコールはダメなんだ without any context, I will understand it as "I can't drink alcohol".

That said, ダメ is certainly an absurdly polysemous word with general negative connotation "not good; don't do; don't work". Alone it won't even tell what is not good to what, so the context eventually matters.

Instead of using your example, I will present a Hatsune Miku song called 胸いっぱいのダメを (YouTube), from which you can have every imaginable shades of the word's usage...

空気が読めないからダメ An insensitive guy (like you) is useless.
心を見透かしてはダメ Don't read others' mind.
ダメダメいうのもダメだ Stop saying "no, no".
その着地点もダメだ That solution(?) is no good either.
無責任な本音はダメ A blatant truth is not allowed.
中学生のダメを ... faults of middle schoolers [accusative]
不老不死ならもっとダメ Immortality is even worse.
焼き肉がほんとうまくてダメ The grilled meat tastes so wickedly good.