Red Flag signs of a Bar girl / Local Talent:
Any girl that shouts at you in the night, especially phrases like
"Hello you!, Where you come from?"
"Where you go? / optional: I go with you."
"Khun ja bai nai?"
All the places listed in BKK, Soi Cowboy, Et al. Pattaya, Ratyong, blah blah. Jomtien Beach.
Women that have had multiple foreign boyfriends / husbands / Casual Foreigner male friends.
Sideline girls, for the most part. Depends. Some of them are less mercenary.
When I was in America, I knew a girl that worked her way through nursing school, working as a "Cocktail Waitress" at a place in Sand Diego that was locally infamous as a hangout for sailors and marines. When she got her degree, she left that world behind her.
In Chiang Mai, all the places on Loi Krokh Road (With the notable exception of My Place Lounge), or The Massage shops within .5 Km of Loi Kroh, or shops on Kampanding Road, and most on Sridonchai Road west of Pantip Plaza.
Any girl that works in a place listed on Chiangmailocator.
Definitely any girl working in the many "Erotic Spas" in CM.
Fishbowls, etc. etc. Most of the clubs have freelancers. Zoe is about 60/40, I think. I stopped going there almost a decade ago.
I am confident in saying it takes years of experience here to figure out what is what, and a few failed relationships (unless you are very picky or very lucky) to find a woman that you can eventually trust.. to a point.
Please note that most Thai women are just trying to help themselves to a good life. you do not have to hook up with a bar girl to lose everything.
Also, lots of Office / mall / kiosk girls are hoping for a nice quiet life with someone to take care, and not usually a foreigner, but the money is nice for them, if he has means. Most government office workers are not taking nightly side income, but many of them are looking for someone to supplement their salary in an LTR, and surprising numbers of them are corrupt within their own domain of power, etc.
Truth is a relative thing also. very difficult to be here, and at the same time be a guy that loves 100% control, certainty, or stability. it takes a while to learn to navigate Thai relationships, and how to hold the reins.
Trading up is a thing. Be wary.