Scams are still alive and well at the Marina Grand (or whatever its current name might be) in Mazatlan.
This past November (2016) my wife and I went there for timeshare presentation thinking we'd make an easy $300 for our time. Instead they pushed all the right buttons, offering to buy both our Wyndham and El Cid timeshare ownership, for a significant sum. All we needed to do was put up 10% of the payment coming us as a fee for the Mexican government; we were told if we did this we could avoid paying capital gains tax in the US. We were to return the following week for the "closing". When we returned we were then told we needed to pay an additional amount as a "transfer fee" in order for our payment to be released to us (this fee had not been mentioned until that moment).
Thinking this was still legitimate we paid that fee. Upon returning home we were then contacted by American Holding Company, based according to their info, in Cincinnati, to continue the final steps. Their representative said the funds would be released to us after we first paid a "Foreign Investor Registration" fee of $52,000 (again, no mention of this fee until that moment), but we would receive this amount back along with the "transfer fee" with the payment for our timeshares -- that's the point at which I finally admitted to myself we'd been taken.
They're simply seeing what they can get out of us by demanding more and more. After researching online I discovered timeshare scams have been happening at this same location for years, even with the Mexican government's knowledge. I immediately asked for a refund, but they stalled for weeks, finally offering to cancel the arrangement if I first paid them $3,600 as a cancellation fee! I repeated over and over we would send no more money. It's now in the hands of our credit card companies in a dispute process.
Bottom line -- don't put yourself in the situation, and if you do don't believe a word they say. On the basis of this experience they're very, very good at what they do; they make themselves completely believable and tell you what you want to hear. Beware of Carlota Vega, Tony Lopez, Larry Davis, anyone else affiliiated with the companies mentioned.