I think the big problem I have with some some agents, is that they don't understand their role. You are a liaison between two people where a big chunk of monies is about to pass through.
I could be wrong, but in commercial realty, if you have to 'sell' someone on a property, you've already lost it. At least in my case, I don't even pick up the phone without committing a huge amount of due diligence on the subject. So by the time I make first-point contact to a broker, I'm privy and hot on the dirt. The only thing YOU need to be concerned with is getting that price to where I want it.
If there's some spectacular fact about the property no one knows about, like jesus lived there one time, then feel free to disclose. Otherwise, an amateur broker can really dig a hole if he's not careful. Like this last broker. He disclosed that the well performance was 750- which he thought was a good idea to share. Except I talked to the neighbors N, S, W and E of the property before I called and they're all pulling 950. My counter reflected that tidbit and I gave credit to the broker for letting me know. lol.
