Really? Are there any statistics over that? At least here, I'd think "internet prostitution" (ie. advertising your services online) is the most common form of prostitution.

Then again here we have legislation against street prostitution, ie. selling of sex services openly in public places (like on the streets, restaurants etc.). That is forbidden but it is not based on thinking of the poor prostitutes, but rather public order keeping the streets clean from unwanted activities. That is, people don't like it if some prostitutes are sometimes even aggressively harassing people going by, trying to sell them sex services. Many other actions are forbidden on the streets on same grounds, like peeing on the streets (even if you do it on the lawn or a street gully; peeing in itself is not forbidden), or having sex in the open in public, or maybe even playing music loud.

So the message is mostly: you can sell your sex services... but please do it privately.

Compared to what? Don't forget that prostitution is generally illegal also in backwater islamic states.

It is a tricky question anyway because you have to consider if you see prostitution as a cause for something, or as a consequence of something (your question seems to concentrate on the "cause" part, ie. allowing prostitution causes something (positive or negative) to the society). If you observe only one country, it is probably plausible to say that when the economy is up, there are less (local) prostitutes (and those who are might make quite a lot of money simply because there are more customers with good income), and when the economy is down, there may be more people trying to get extra income from it, including people who wouldn't otherwise want to have anything to do with prostitution, but the prices for prostitution would also go down as there are less people willing to spend money on it, and more people offering the services.

Then again, if the economy is down and some people seek extra income through prostitution, is that a positive or a negative thing? What if the other option is not having any income at all, or doing some criminal acts? Does making prostitution illegal in such a situation really help anyone?

Having said that, maybe Thailand is one example where prostitution is tolerated... at least more than in most other countries, and prostitutes themselves face less "slutshaming" than in other countries, even if there people don't necessarily want to publicly announce selling sex services (to their relatives etc.).

After all, in many western countries one common question by anti-prostitution people is "Would YOU marry a prostitute?" (as if it is something unthinkable no western man would ever do, as prostitutes are just filthy and whatnot), and I feel in Thailand it might not be such a big deal for many (local) men. In fact, since it is customary to send some of your income to e.g. your parents, it may sometimes be deemed even positive (that someone is doing it), if it helps their family back home.