I haven't really had a positive LEO encounter unless you count the fact that the LEO doesn't notice or doesn't say anything about me carrying. I have however, had the below experience...
My wife and I headed out to do some grocery shopping, with me OC'ing my Glock .40. We stopped at the Wal-Mart at SouthPoint, with no problems, and had dinner at the Golden Corral off of 126 also with no problems. (The food's not great but the wife is pregnant!) Our next stop was the Bloom at Lee's Hill (Just off of 126). We usually go there for produce as wal-mart doesn't always have the freshest veggies. My wife and I were inside for maybe 10 minutes getting a few last things on the list when it happened...
As we were checking out a young man (I'm young myself) maybe a manager, introduced himself and told me that someone had called 911 about a man with a gun and he wanted to make sure I was licensed to carry. He said that he had no problem with me carrying himself but he was asked to check. I told him that Virginia does not require licensing and he said Ok and went back to the phone.
We then took our groceries and proceeded to the exit. When we walked out of the store there were two Spotyslvania County Sheriff's Deputies and what appeared to be a Detective (Plain clothes with a badge on his hip). The youngest officersaid something and motioned for me to come speak to them. I walked over to speak with them and the older officer asked me if I was in law enforcement. I told him "no" and then the younger officer told me that he knew I wasn't breaking the law but they had received a call about a man with a gun and were investigating. He asked me why I was carrying and I told him "for personal protection". He asked me why I don't get a concealed carry permit and I told him that I have a CC permit but that's not always comfortable and you can't CC everywhere that you can OC. He nodded his head and asked me if he could see my ID. I know I'm not legally required to, but I was very nervous so obliged. The youngest officer nodded his head and stepped back to "Call me in" (I heard the radio traffic come back with my CC on file)
At this point the detective was in the background watching the whole thing and the older officer walked up and told me that Spotsylvania County has a register of businesses that do not allow handguns on their premise and they that I shouldn't carry here since they had called 911. I informed the officer that I don't know anything about such a register but that if Bloom does not want me to carry in their store they can ask me to leave and I will oblige, otherwise I am not breaking the law and within my right to open carry. He then sent the younger officer inside to see how Bloom's manager felt. The older officer then told me that in Spotyslvania county if the business is on the register I cannot carry there. I told the officerthat Iunderstand the private property laws and if they don't want me to carry there they can post a sign and I won't carry, or they can ask me to leave and I will. He responded that they are not required to post a sign. I said that I understand that they are not required but Ialso know that if you OC in a business even if it is posted the only thing they can do is press trespassing charges if you refuse to leave.
At this point he asked me if I was a lawyer and I told him I was not but was familiar with the laws for this very reason. He seemed to be getting a little upset and then said, in a snide way, that we could sort the whole thing out in front of a judge. At this point I was a little mad and nervous and told him that I would be more than happy for him to detain me or even arrest me for not breaking the law.
The younger cop made a perfectly timed appearance and informed me and the older officer that the manager of the Bloom had no problems with me carrying my gun there (WOOHOO!). The older officer then looked at me and told me to have a nice day. My wife and I walked through the parking lot (with all of the eyes of the gathered crowd on us) got in the car and drove home.
The rest of the story is that I contacted the Spotsylvania County Sheriff's Department about the "register" and was told that it did not exist. Every officer that I had contact with during this experience was a complete professional, with the exception of Officer Jones.