I'm actually curious brothel advertising aren't utilising Google Analytics to calculate their return on investment. All businesses do it now as you'd want to be able to calculate your cost per conversion by channel to maximise bang for your bucks in terms of marketing spend. Impressions aren't good enough anymore these days. Channel attribution is the way to go (even that gets complicated and there are various ways of calculating channel attribution. You can do first touch, last touch, time decay attribution etc.).
Some shops could even at the most basic include UTM parameters in the URLs of the girls they're advertising on for example in the Sydney - Shop and Girl Info section. They could then pass that data to GA and determine at least how many hits to their website were as a result of say for example this forum.
Famous Youtubers also gets sponsored by different products and assigned their own promo code which gives a small discount but also again helps the marketers attribute sales to their marketing spend. If 10,000 purchases came to their site using a promo code of a specific Youtuber then they're able to determine the usefulness of said Youtuber.
We should do the same for AR advertisers. Will be a bit tricky to work with as it would require some form of online booking. Even some Escorts who advertise on multiple sites now include as part of their bio for punters to also include where they saw their ads.
It's mind boggling to think that shops aren't implementing this. Advertising effectiveness whether it be ads or sponsoring someone to write a AR should be measurable, otherwise you're just throwing money into the dark.
