I just bought an e91 a last thursday. I was dealing with a local dealership and one that was about 1.5 hrs away. The one further away, I dealt with over email. Good for some, not for others. In this case, the guy was a complete ass and was expecting me, the buyer, to bend over backwards for him. He came off as pompous and like he was "the shit." He offered me jack on my trade in and was over pricing the car. I asked him about KBB and is response was "what are you trying to accomplish?"
The local guy on the other hand, I dealt with in person. He was much more forthcoming (even though I knew he wanted as much as possible) but was willing to work. They recently marked down the car so were hesitant to move on it but it had been sitting on their lot for over a month. At first he low balled me on my trade-in but I was able to get it to a reasonable price. I was also able to get the car down about another $1k. In all, I was happy with the way the salesman treated me and with how the negotiation went.
For salesmen out there, buyers don't like bullshit. Tell us your absolute rock bottom price and we will leave if we don't like it or buy if we are agreeable (even though I don't mind a little haggling). For buyers, don't be assholes. Do your research, and go in with a price in mind (that's reasonable). If your first choice doesn't get you the price you want, then find something else in your range.