Many listings look the same
We hear this a lot, especially from North American clients: In the Dominican Republic there is no MLS and consequently properties tend to be listed by many different agents and agencies. Be wary of properties that you might see with a lower price than with other agencies. Prices are usually the same and backed up by a contract so it's odd that one agent might be selling at a different price.
You don't have to use any one particular agency. If you see a property on a site that you like you can always ask another agency to show it. That's how things work here - it's usually better to go with the people that you think you will be happy to do business with. If it doesn't feel right then walk away.