I don't understand why a SA wouldn't have plenty of time to answer any semi-reasonable question but I would try and be flexible on timing. During the day during the week, I strongly suspect they have all kinds of time. On the evenings and particularly on the weekends I believe they may be busy and may not want to deal with a lot of questions. There is some information, like on a particular car they have, that you have to get from the SA. But I ordered one so I mostly just looked things up myself. I haven't found information from SAs to be very accurate so I prefer to just look it up. But some people prefer to talk about it and the SA should be open to that.
I think a dealership that wouldn't address questions during the day during the week doesn't deserve business. But I would be symphathetic to their busy periods if I had time consuming questions, at least until I am ready to buy. I've also found you get their attention nicely if you tell them early that you are willing to buy if they can come up with the right deal. Conversely, I've also told them when I wasn't and when I would be. It seems to go better if you're up-front about where you are. I've received lots of attention even when I said I was just gathering information but it was when they didn't have lots of other customers in the dealership.
128i Convertible, MT, Alpine White, Black Top, Taupe Leatherette, Walnut, Sport
Ordered 5/22/09, Completed 6/4/09, At Port 6/9/09, On the Georgia Highway 6/13/09, Ship Arrived Charleston 6/24/09 at 10pm, PCD 7/21/09