Human nature and man's dependence on money pretty much ensures that greed and avarice will endure. In the absence of enforced regulations, codes of conduct and direct consequences for professional excesses, the real estate market in this country is a minefield.
The saying I heard not long after arriving in this country and that sticks with me to this day:
"A local will take you for a 1000 pesos, a foreigner will take you for a 1000 dollars"
Whether you are buying a table, chair or a house, the purchaser in this country is solely responsible for determining the best possible price or choosing to walk away and look elsewhere. No one here other than you is interested in or focused on the lowest possible price. You cannot rely on the advice of someone whose own personal interests are in direct competition with your own when they are not governed by a code of professional conduct that protects their clients and allows for some sort of redress if that client is taken advantage of.
This is the same for many professions in this country. Builders, lawyers, plumbers, electricians, police, doctors, judges and of course let's not forget the politicians. All operate within a nebulous environment with limited or nonexistent accountability for their failings.