If its not immoral to use drugs it shouldn't be immoral to talk about it. "Trashy" is just an label for behavior deemed unwanted or associated with low class. But the parent (presumably) deemed using drugs not trashy by his own admission of using them.
It's also not immoral to have sex. It would be, at a minimum, very odd to share the blow-by-blow details of such activities the prior weekend with an interviewer. I don't think I'm being a prude to say I would probably close out that interview as soon as reasonably possible and move on.
By my definition of “trashy” - it’s only “cool” to share the fact that you had sex with someone when you’re 15.
Same is here: I can imagine many situations where discussing the effects of drugs and your experiences of them to be interesting. But “I spend a weekend dancing with molly” sounds more like a 15-year-old just got access to sex for the first time.
I don't take the "dancing with Molly" as a blow-by-blow, more like an acknowledgement of a certain activity. But I wouldn't take acknowledging that you had sex to be trashy if relevant to the conversation. But the the interviewer made the dancing response relevant when they asked if they did anything noteworthy over the weekend.
> If its not immoral to use drugs it shouldn't be immoral to talk about it.
I don't think I can agree with that reasoning in the context of a job interview. I wouldn't want to hear about your sex life either, but that doesn't mean you can't have one.
