I think the problem is likely stigmatizing sex workers as less desirable which is sort of narrow-minded and perhaps dehumanizing. There's a large imposition of morality that isn't necessarily shared by everyone.
Conversation is pointless as OP has now responded saying he simply doesn't like hearing about sex.
To use a hypothetical example - a cereal company puts some tasteless comment in an unobtrusive corner of the box. You don't have to look at it if you don't want to - you can turn the box, or put the cereal into another container, or just not read the box that closely. But why would you want to when there are 45 other brands of cereal on the supermarket shelf?