> However, I don't think from that it can be inferred that the message is "women are only useful as prostitutes".

Nor do I. That would've been misogynistic, and my whole initial point was this ad is sexist but not misogynistic.

> Probably at the time secretary was still a common job, and most of them were women. In that light maybe it also is less shocking - about as shocking as displaying a female teacher today.

I disagree, a teacher caressing a student in a college ad would be out of place today (although there's a whole subgenre of porn about it).