There was no TER back when I started paying for sex. Hell, there was no internet!
Nowadays it's actually a lot tougher. The streetwalker scene is pretty much gone as far as quality women go and Back Page is about 95% BS. I Have been sticking with my ATF, a few other favs and some reliable agencies for quite a few years now. Still, If I saw an ad that intrigued me and she had a legit web site and/or advertising history I might take a chance.
As far as rolling the dice on a BP girl with no other verification? Absolutely not!