I have clients addicted to those kinds of websites, they pick properties by looking at their cell phones, asking me, some of the answers from me "sold more than 1 year ago", "no, it's not active, pending, someone is already buying it", and some properties on the market but not there. They are good to give general idea how the market is, but not to make decision which property to buy without a local agent.
First off all, for buyers, our service fee is free (seller pays it, or bank owned bank pays it). So it's better to work with local agent. Those web sites try to get a piece from real estate market, so the fastest and easiest way doing it to discount the service fees, pay back some commission back. Logically, if you know from the beginning that you will be paid less, how many of people work full amount of worth for less?
The other point is, the seller's agent works for seller's best interest, buyer's agent works for buyer's best interest. Some people try to find listing agents and want to work with them, because they think they know better about the property. But what they miss it, they are committed to work for seller's best interest, they can't help for many details, they can't negotiate the price. When this service is free for you and can get full service, what's to point to be in that situation?
The best thing to do is, if you are a buyer, work with your own agent, make sure that person is really dedicated his/her time, energy, knowledge, expertise to you and please do the same thing, too. That's how you get the priority and the best deal. there are more stuff involved than just finding a property, and even more involved how to find and the next step process, the really special ones don't disappear after selling it and ready to help more. They educate you from how the process works to how the current market is. But if you are not loyal to your agent and try to work with for more than one agent, you will be wasting your time and their time, the result will be fruitless for everyone.
If you would like to talk about more and I can also give more info about the differences between NY and CA how the things work in real estate. I used to live in Manhattan and invested in NY state. :
166 Canon Drive
Beverly Hills, CA 90210
310 428 6573