I actually had quite a bit of trouble finding a MT school without a graded system. I have seen schools with them that produce good fighters, but those schools (obviously) have dedicated fight teams - no one training in a gym with active fighters is going to think their 'black singlet' means **** compared to people winning real bouts. I've also seen MT schools with graded systems that don't fight (or only do the odd padded interclub type thing) and those guys do often have a warped idea of their own abilities. But I'd like to think those guys will eventually go to a real fight show and work out which gyms are producing good fighters (ie not theirs) and what good fighters look like (ie not them). I've known plenty of people who've left those gyms to join proper fight teams.
Ultimately, as long as people are still competing in MT, it will be pretty easy to tell (to anyone who bothers to do the research, anyway) which gyms actually walk the walk.
The bigger issue I see is gyms that say they teach MT, wear Thai shorts and whatever, but don't actually teach elbows and proper grappling and never enter fighters into Full Thai Rules fights (or even Mod Thai, a lot of the time) and make a farce of the wai khru and pre-fight rituals. Some of them produce fine kickboxers, but they're duping their students, and the distinction between learning KB and MT isn't going to be immediately obvious to the majority of people.
I'll concede I'm out of the loop, but I return to the West shortly. Should be interesting...