Sofia and a question

Sofia Coppola, in Fendi.

Amy Winehouse and Karl Lagerfeld, also at the Fendi fete in Paris.

Which brings my question: I was recently considering wearing a bra under a strapless dress. (By recently I mean today.) I suspect a little freshness there but it teeters on stale. I think as long as it doesn't get too Dolce and Gabbana, it remains acceptable.

Noway. Don't do it. For some reason, showing bra seems more daring than having a neckline that falls at your belly button. How does that work? Am I right?