Not cracking on you, SixClowns, just continuing the discussion.
The illegal use of cocaine is indeed wrong. But the substance itself is not evil--it is merely a substance. "Things" are just things. Cocaine can be used legally, medically, and responsibly to treat pain.
Paul points out that from a Christian standpoint that all things are permissible, but not all things are profitable. Is it unprofitable to have a beer after mowing the lawn on a hot day? If you are an alcoholic, the answer is no, but if you are not, a beer doesn't harm you and can be mighty refreshing.
I think far more harm is done worrying others about a beer or a glass of wine that they take which is legal for them to consume, causes no harm to them or others, and is not used abusively. Being a Christian drunk or any other kind of drunk is unprofitable, not only to one's self but to one's family and society as a whole. But a little wine hurts no one except for an alcoholic, who can't stop at a little, or a person who might have a medical condition where wine would interact with a medication they were taking or worsen the condition itself.
Personally, I can think of a few Christians I know who would be vastly improved by the addition of a little wine. Perhaps they might even get over themselves and past obsessing over such small things.