Do I have to pay a broker who's working for the landlord?

Of course you do.

You can ignore the genius above. If the lease you sign doesn't mention payment of a broker fee, you don't have an obligation, assuming you didn't sign a contract with a broker.

I am an agent. If you saw the apartment through an agent or it is that agents exclusive, you must pay them. Leases never mention the fee. That has nothing to do with it. Even if you later find it was an open (non-exclusive) listing but you saw it through an agent, you owe them.
Be careful not to see properies though more than one agent, or if an agent tells you they will get you an apartment you already saw with someone else for a lower fee. You will end up owing BOTH a fee.
Try to work only wiht REBNY (Real Estate Board of New York) agencies, it is the ethics organization for Real estate in NY. Be wary of agents who seem to never want to show you what you called on, bait and awitch, or the obvioulsly ignorant and untrained agents, you will know the 'hothouse' operations.
Do not waste your time buying silly books with lists of the major landlords, they do not want to deal with individuals, they want you to use an agent who will do the work for them. Most of their apartemnts are overpriced anyway. I give out the names of their buildings for free, that should tell you what they are worth!
In this competative market a good agent will get you the apartment. Landlords do not employ people to sit on the phone explaining the market to you, describing apartments and going over the process. They want quaified applications with back up verification delivered whole. The ones with on-site offices are really overpriced...you are paying a fee, it is just in the rent!
Best of luck in your searches, I know it is tough. I have been there too, and I remember how some treated me. I have been very careful never to do that. I will not give my name, I only work on my own exclusives, signed agreements with owners. So I do not really want a flow of customers--I just wish there were more seasoned rental agents out there, most who are decent change to sales. Most of the rest are horrid--I know they call me to show my listings and they never cease to astound me!

Clearly you are an agent. Because only an agent wouldn't understand that to collect a fee you need a contract. If the renter did not sign a contract with the agent, no fee is due. The agent has no moral or legal basis to ask for a fee if there was no agreement. Further, you are incorrect in your statement regarding landlords. Many buildings have on-site management that do deal directly with tennants. In my experience, most downtown buildings were very happy to show both model apartments and upcoming vacancies. We just walked in and asked. And since they are already going to have to do the background check, they don't care if you use a broker or not. And the idea that most landlords that deal directly with tenants have overpriced apartments defies all common sense. Landlords have an incentive to price the the apartments to rent. It's a very simple economic concept.

If I were a broker, I too would spread the misinformation above, but it's mostly nonsense.

It's not nonsense at all. My experience is that both of your assessments of rental landlords is correct, because there are all types. There are those who would prefer to keep their costs as low as possible, and those who wouldn't think of it, if it meant they or their staff would have to be more involved. Just because your experience is different, doesn't mean the agent is spreading misinformation.

I find the whole anti-realtor stance that many take to be quite tiring. Go on to education boards and they are trashing teachers, everyone piles on lawyers, and here its far too often the same. I'm a self-professed real estate expert, just like every other New Yorker I know, but even I know that there's always lots to learn, and personally look forward to the experience of those that are in the business for real.

Ok, now go ahead and say "you must be an agent", it's not true, but it will keep you warm tonight.

What a bunch of bull about it not being worth it to deal with the larger landlords/no fee buildings. I have rented several apartments in NY and it is true that some of the larger buildings that do not charge fees are expensive, but that is moslty because those buildings are newer and offer more amenities. Dealing with a no-fee building/landlord saves you money (no 15% fee), saves you time (you can go right to the building to see many apartments often), and allows you to avoid using a broker that may just not be that good. There are plenty of good brokers out there, but many are inexperienced and not helpful - all for thousands in fees. And I can't tell you how many times I have seen brokers with clients in the no-fee buildings I have rented - they still charge the full fee despite the fact that the client could have avoided the fee if they did a little work and found the building on their own (with those silly books or the internet).

Exactly right. Brokers offer a conveniencee, no question. And if you have the money, it's alot easier to have them do the work. But really, you can do it yourself and see virtually everything you would have seen with a broker. It's just harder. That's my experience. But the original question of paying a broker fee when you didn't agree to one is obvious. You don't pay unless you have a contract. And what gives brokers a bad name is when they give such obviously stupid answers as above implying that you must pay. A fee is negotiated. If there was no negotiation and no contract there is no fee. Any broker that aruges otherwise is just plain wrong.

If a landlord/owner signs an Exlcusive Right to Lease Agreement with a broker, he or she customarily agrees to refer all inquiries and conduct all negotiations through that broker. Most exclusive agreements state that the fee is paid by the tenant but that if the owner leases the apartment to anyone they didn't refer to the broker, then the owner pays the fee.