Like others have said - it usually comes down to common courtesy and relativity. Most people now a days only think about themselves and have no care for the people around them. IE: Being late, no show, no call, changing price once they are in you home. (That being said, I've never really had a bad interaction with any RC'ers and I attribute that to they are hobbyist. They usually understand that we all care about the items we are getting and care not to step on toes of people we know we are going to see again.)
As for the driving concern in the Valley. Someone, brought up a good point that the valley gets smaller the more you know about it. I think I should let you know, I'm a westsider (Peoria). I have and will continue to drive all over this valley for things. My problem is timing. Although, something may be a great deal, I can't afford the time to drive out to QC to get it (working a 8-5 and have my own business). When we were really active in the hobby we used to take an entire Saturday and try to hit all the stores we could on the east valley, pick up frags from others and see other's tanks.
One last comment - I believe that it is the "Poster/Seller" obligation to give ALL the information up front in their post. Location being included; Especially with how large of an area the "Valley" covers. I personally come across this issue all the time. My first reply to most posts are "where are you and when can I pick up?" Not "I'll take it" and then later back out because you are to far away.
Please let me know your thoughts on this!!! - But doesn't everyone understand that when you include every last detail you can think of in your post: 1- You are going to get more serious replies. 2- You are not going have to sift through a ton of questions. 3- No one can say "well you didn't post that".
Sorry for the soapbox, but I just had to give my 2scents.