D2864, I must disagree.
I think the worst behavior is that which directly affects another person. I go about mongering (the actual act from negotiation through seeing the girl to a taxi) very discretely and quietly, using all the good manners Mom taught me.

Okay, okay... Mom didn't actually coach me on how to handle dealings with a hooker, but you get my meaning. My mongering doesn't get right into the face of locals, except of course with those who work in "prostitution support" i.e. restauranteurs, hotel staff bartenders and taxistas.
I see the "ugly tourist" behavior as being far worse. First of all, regardless of venue and situation, this kind of ugliness can be readily found. It's more widespread and therefore more pervasive.
While many locals may frown on prostitution for moral or political reasons, most never are confronted by the business itself. On the other hand, any shopkeeper, waiter, driver or tour guide will frequently be confronted with ugly tourist behavior, whether within the sphere of prostitution or not.
It goes beyond apples and oranges, and whatever your feelings about the "shamefulness" of prostitution, you must agree that even this "evil, exploitative and nasty" behavior can be done with gentlemanly manners, diplomacy, good comportment and a sense of style which are inoffensive to the majority of locals.
D28XXX, I see a lot of self-loathing in your posts, and while I can agree with some of your feelings about prostitution, I cannot help but feel sorry for you. Perhaps another hobby that is less decadent would suit you better? I am not flaming here and mean no offense, whatsoever. But I do believe that you're projecting a lot of your puritanical hang-ups into a discussion that should be centered on how we conduct ourselves abroad, whether or not we're paying for play at the time.