NISoP. Adjective + Prepositional phrase as adjunct. DCDuringTALK 17:15, 27 June 2011 (UTC)
I think it's too idiomatic to be SOP. The individual parts bad, for, and you do not really add up to the meaning "unhealthy", and note that the pronoun doesn't change its grammatical person: "He doesn't eat sugar because it's bad for you" is a perfectly natural sentence; the listener wouldn't reply, "Why should he avoid sugar just because it's bad for me?". The phrase is always "bad for you" regardless of the person and number of the rest of the sentence. —Angr 19:55, 27 June 2011 (UTC)
As we do not have canonical forms for definitions and don't even seem to believe in substitutability as a desideratum, it is not easy to combine definitions to show that an MWE is NISoP.
The use of you to mean "one" is not limited to this phrase. For example, we have some 20-odd proverbs that begin with you in this sense.
"Bad" and "good" are not the only terms that fit in the AdjP slot in this construction ([AdjP for NomP]).
As a common collocation and a good example of this use of "you", this phrase should be part of usage examples at [[you]] and/or [[bad]] and part of some wiki's phrasebook. DCDuringTALK 20:36, 27 June 2011 (UTC)
For now, I've added a usage note to bad. Feel free to delete that usage note if you add a sense — "unhealthy or poisonous"? As for the entry [[bad for you]] — like Ruakh, I lean weakly towards deletion. - -sche(discuss) 23:44, 28 June 2011 (UTC)
I like the idea of usage notes. But I hope that "eating arsenic is bad for you" is deleted. Being bad for you and being deadly are different things. Also, we're missing the sense of "bad for you" meaning too bad, lough luck. —This unsigned comment was added by Angel drinks (talk • contribs) at 00:22, 29 June 2011 (UTC).
Keep per Angr, assuming that "the pronoun doesn't change its grammatical person", and the following sounds natural: "He doesn't eat sugar because it's bad for you". --Dan Polansky 14:04, 29 June 2011 (UTC)
That does indeed sound natural. This is the generic "you", meaning "people". ("He doesn't eat sugar because it's bad for him" is also fine, but with a different meaning: there it means that it's specifically bad for him; maybe he's diabetic, say. Or, alternatively, it could imply that he's a child or imbecile — the implication being roughly, "He doesn't eat sugar because his mother told him it was bad for him." Incidentally, we can also say "it's bad for his diabetes" or "it's bad for his teeth", both of which are more specific than "it's bad for him".) —RuakhTALK 14:31, 29 June 2011 (UTC)
You seem to be saying that "He doesn't eat sugar because it's bad for you" uses the sense of "you" that reads "(object pronoun) Anyone, one; an unspecified individual or group of individuals", as exemplified in "They always smile at you when they serve you in this restaurant". It does not sound quite like that to me, but I admit that replacing "you" with "one" in the discussed example sentence works fine. But even if I admit this point, I still do not see how "bad for you" automatically becomes "unhealthy for you", meaning "bad for your health". Would someone say "He avoids playing roulette because it's bad for you", meaning "bad for your finance"? --Dan Polansky 14:59, 29 June 2011 (UTC)
That's polysemy for you. "Bad" ("generalized negative valence") can have many specific meanings, each of which has a negative valence. (And, in slang, it can flip to positive). DCDuringTALK 15:48, 29 June 2011 (UTC)
Polysemy--the ability of words to carry several meanings--is what we document here in Wiktionary: if a word has several meanings, we define them. In "bad", Wiktionary documents several senses that capture some negative or undesirable property, including "6. Faulty; not functional", "7. Of food, spoiled, rotten, overripe", and "8. Of breath, malodorous, foul". A look at MWO's entry for "bad" shows that most of their senses of "bad" capture some negative or undesirable property, so might be declared superfluous per your argument. Furthermore, you may check whether you find the analogue of "it's bad for you" in the sense of "unhealthy" in any of the non-English languages that you speak. I find no analogue in Czech and German, which leads me to believe that "bad for you" in the sense of "unhealthy" is peculiar to English. Finally, if "bad" can flip to positive in slang, we should better document it; I cannot recall that the Czech analogue ever does that. The positive use of "bad" that you have in mind may be related to "9. Bold and daring", exemplified in "Did you see what he wrote on that guy's forehead? What a bad ass!", from Wiktionary. --Dan Polansky 17:56, 29 June 2011 (UTC)
Of course we add multiple meanings. The only condition is that the sense be a meaning not determined by context. Bad (“unhealthy”) is not always so determined, so it should be included, as it is in the more complete dictionaries that I consult for a more complete, non-duplicative, and balanced presentation of polysemous words.
But we only had 10 senses in our Etymology 1 vs 16 for MWOnline. But as long as we remain a dictionary in our mission we don't document the polysemy of every non-idiomatic collocation. That's what the human brain does. If no one volunteers to add all the senses of bad, that makes us an incomplete dictionary, possibly even a bad dictionary.
Lots of things are peculiar to English but NISoP in English. My knowledge of German is inconsequential, even dangerous to the extent I ever have any confidence in it.
We already have documented the valence flip at bad#Etymology 2, that being the kind of "fun" thing that folks like to do. Even there we miss one of the two senses that MWOnline has ("tough"), which fit my experience, FWIW. I've long wondered about the validity of Etymology 2. It seems more likely that it is in the contrary-to-dominant-culture nature of slang (in this case AAVE) for the valence flip to have developed. DCDuringTALK 19:09, 29 June 2011 (UTC)
Delete. It's as SOP as SOP can be. · 19:37, 29 June 2011 (UTC)
Delete. What's bad for Wiktionary is not good for Wiktionary. Equinox◑ 22:15, 1 July 2011 (UTC)