Hi Will,
The main reason that investors use bird dogs is that they are basically free or very inexpensive labor. It is like hiring a commission salesman. Some bird dogs are lead generators; some are paid only if they bring a deal that the investor closes on. It is also better to have five people looking for good deals instead of just one.
I don't know of any investor who pays a bird dog for an MLS lead. There is no reason to do so. If a deal is in the MLS, a real estate agent is going to get a commission. Most investors have their own real estate agent looking for great MLS deals for them (or they have access to the MLS themselves). Why pay an extra fee?
The real value of a bird dog is that they can find either the specific type of deal an investor is looking for or deals that others don't know about. We are in a sellers' market right now and some people wonder why an investor would use a bird dog. But with so many people upside down in their houses and/or behind in their payments, true good deals are not as easy to find as an outsider would think.
Bird dogs turn in all levels of leads, from something as simple as an address and a few notes on the property to more detailed information such as the address, the owner's name and address, pictures of the property, and any other data on the property such as info from the tax appraiser's or tax accessor's sites. If the bird dog is working as a lead generator, he may be paid varying rates depending on the depth of information and whether or not the investor closes on a deal.
Can a bird dog just go through websites and find deals? Possibly. Most investors would rather spend their time negotiating deals instead of doing administrative work. Frankly, I can pay someone $10 an hour to do that; it is not something I would pay a bird dog for.
If you are going to bird dog, you need to first check the laws in your state to see if you can legally accept a fee for finding properties if you are not professionally licensed for real estate. There are legal ways around this, most notably putting a property under contract and assigning a contract.
I think bird dogging is one of the best ways to learn if real estate is the business for you. Of course, I am a little prejudiced -- I wrote an ebook on bird dogging. But, you can learn the market, make money without having to invest much more than your time and establish contacts with other investors who you can learn from. Give it a try.
Best of luck to you,
Barbara