I'm not sure if we've been here before, but still...
'I couldn't care less about alcohol' translates to 'I have no interest in alcohol' ('It would be difficult for me to have less interest in alcohol as, by implication, I have none'...)
Therefore, in opposition, 'I could care less about alcohol' means (to me...) 'I am very interested in alcohol'.
Maybe this explains some confusion here. A strange expression, which seems to have come to mean exactly the same thing, to some, despite their being opposites. It's no wonder that World Wars flare up occasionally.