Op clearly has an opinion here thats not going to be changed so speaking generally, for any other person who has this experience, I think if an acquaintance tells you they have a job that you don't respect, the correct recourse is to be civil. If you can fake it and say nice things to the other person, that's great. Of if you can just muster one nice comment and then some bean dip, thats ok too. Of course, the etiquette is different for a close friend, but that still doesn't give you carte blanche to be a jerk.
Of course, the odds that an acquaintance comes up to you in the grocery store and announces that she's going to be a phone sex operator are low, bordering on unbelievable.