Traditionally, buyers would stop at a condominium for sale and be shown the property by an agent sitting there. But the problem with that method is that the agent sitting there is usually the listing agent. And in most cases, he or she represents the seller.
Be careful about what you say to a listing agent. A listing agent's role is to find a buyer, and to get as high a price and as good terms as possible for the seller. He or she is required to inform the seller of any facts that may influence the seller's decision about whether to accept an offer or not.
For example, if you mention to the listing agent how much mortgage you are qualified for, don't be surprised if the seller knows too.
Always keep in mind that you want the lowest price and the best terms. If an agent is not directly working for you, they could very well be working against you.