Title issues

The explanation of your plight is a little short on details, but it is probably safe to say that at any Mexican beach resort it is "common" to find scam-artist realtors and fraudulent developers. Zihua cannot claim exemption from that.

Separtely, the legal system in this country -- including land title -- can be a confusing, tangled mess to negotiate for locals, let alone foreigners.

Some basic rules: Always deal with on a reputable real estate agent on any transaction, and even contract an outside lawyer for additional advice. NEVER "leap before you look," and NEVER buy a property "off the drawing board."

I would like to add some color to your post.
As far as I know, real estate agents are not a 'licensed' profession in Mexico in the way I think of it in the USA.
Although I do think there are some Mexican and even possibly non-Mexican individuals who have some kind of 'certification'.
Anyone can claim to be a real estate agent.
So reputation is everything.
Please correct me if I am wrong.

As regards buying "off the drawing board", I did so because the architect/builder was well known (Zozaya) and I had seen some of his other projects which I admired- and who doesn't like a (pre-construction) 'deal'?
For the most part I have been happy with my purchase. Not without issues however.
So I guess it depends on an individuals tolerance to enter into a bit of the 'unknown' in a field where there may not be many knowns.

Maybe you've noticed I don't recommend the architect you mention. He's shown a lack of ethical principles too many times for me to be able to list him or recommend his services.