When someone is hired, they expect to get paid and generally speaking they are accountable to whoever is paying them. Real estate agents are different, they work for whoever signs an agency agreement with them which is not always the same person paying. And the distinction is not simply a matter of money.

When an real estate agent works for you, you are called a client. A client, through the agency agreement, is owed certain fiduciary duties real estate agents call OLD CAR:

OBEDIENCE - Obey legal real estate related instructions.
LOYALTY - Keeping the client's best interest first, ahead of any other party including the agent themselves.
DISCLOSURE - Communicate to the client any and all information which may benefit them in making their buying/selling decision.
CONFIDENTIALITY - Keep secret information about the client.
ACCOUNTING - Accurate tracking of all documents and funds in the transaction.
REASONABLE CARE - Provide competent knowledgeable advice and guidance throughout the transaction.

If you have not signed an agency agreement with your realtor, you are not the client, you are not entitled to the OLD CAR protections and benefits and the realtor you are talking to is most likely legally obligation to work for the other party. While realtors working for the other party are still obligated to provide you with fairness, honesty and disclosure of material facts, they are also obligated to information the other party of any information they learn about your price, terms and motivations which ultimately hurts your negotiating position.

Find out how to protect yourself by being a client in "Becoming a Client with a Realtor Agency Agreement"