One month later ... this is turning out to be a real challenge. I'm not much closer to finding out how to evaluate (other than word of mouth) a dentist in another country. Herewith sharing what little I have found out so far.
There are websites like Dental Departures and WhatClinic, but they're pretty vague on what they base
their choices on. And the reviews are like North Korean election results -- everybody gets five stars all the time -- how are you supposed to take that seriously?
There is a Mexican dental association (
https://www.adm.org.mx/) but the page where they list their certified members is "under construction" and they don't respond to queries.
There are occasional reviews on Yelp, Google, and TripAdvisor, but they're usually not very substantive. I'm amazed at how much people, including rich people, will throw caution to the winds when it comes to choosing someone to dig around with a sharp piece of metal an inch from their brain. Oh, my wife's cousin's hairdresser went to Dr. Dracula, he had such nice manners! OTOH, somebody gets multiple positive reviews is probably at least worth checking out.
(Granted, I'm on the eastern edge of the border, and there seems to be more info for western places like Los Algodones and Tijuana.)
I've been to two dentists so far, both well recommended on the referral sites. One seemed very professional but scarily open-ended on prices. The other seemed less than pristinely clean, told me stuff that doesn't jive with what other dentists have told me, and there was a loud-mouth snowbird who kept demanding attention the whole time they were working with me (he was supposedlly finishing up when I came in, and was still going strong when I left), and they did nothing to manage that, so I didn't really feel like I had their full focus. They had a high Covid-prevention rating on a referrals website but I'd rate what I saw at "B" at best.
Also, the specialized services these places advertise aren't always in-house, and the people who initially evaluate you don't seem to have specialist knowledge but seem to be working from some kind of basic protocol (well, fair enough, it's a free exam, and the exam alone could cost several hundred dollars on the US side). And for e.g. an implant, additional services like a bone graft or sinus lift could easily double the price of the thing, and it's not clear when you find out what the real bill will be. (Yes, I have to ask more questions, and I will. But you sure have to be alert and assertive just to figure out what questions to ask. And it's no quick or simple process.)
So far I've had two X-rays (pretty casually done, no lead apron or anything) and now I'm wondering if I should try a third dentist or will I end up glowing in the dark. Granted, I'm no fan of US-side dentists either -- telling you you need $15,000 worth of work to have quality of life, meanwhile neglecting to mention that the tooth infection you're shlepping around could cause serious harm, grrr! -- and I know for such a steep discount there have to be some compromises (though presumably not with your actual health). It's just surprisingly hard to get the information you need to make a good choice.
Meanwhile, who do you think picks a dentist or a pharmacy based on those carnival-barker-style shills who stand on the sidewalk saying "hey lady, need a dentist?" Somebody must, or they wouldn't keep doing that. It boggles the mind.
So I'm pretty freaked out right now, but I'm sure I'll sort it out. Thought I'd just throw this info up here (for what it's worth) (not much, I realize) in case someone else goes down this path later.