I have a couple...
Down the street from the house I once lived in was a house a drug dealer lived in. The house, for some reason had a drive way on either side of it, although, one was dirt covered, and was never used until said drug dealer moved in. However, this drug dealer was the best neighbor that one could ask for. While it wa a revolving door during the day, in one driveway, and out the other, by 10 pm, his lights were off, and traffic was no longer and issue. There were never any fights and the kids that lived there were really well behaved.
The house across the street from us, a few years later lived a lady and her boyfriend, who would smack her around. We called the cops on that couple planty of times. One day, lady of the house comes over, with a baggie and says she found what she thinks is crack in a couch she got from her BF's sister. Unsure of what to do, we call the police nonemergency number. They said they would send and officer out to collect the drugs. The cop that showed up was the "biggest male appendage" he could have been. He cops this stupid attitude with a bunch of giggling women over this baggie of crack, none of wanted around, because we all had kids. He said something along the lines of this being a serious matter, and my BFF says to him, why do you think we called you guys. We don't use it and we don't want it around our kids. You could tell not a one of us used the stuff either. He finally took the stuff and left.
Same street, many years later. Ex Hubby and I had bought the house across the street, but next to the one in the above story. I wake up one night, and my bedroom looks like a disco. I look out the window, and there are so many flashing vehicles, I thought the old house we lived in was on fire. I went downstairs and asked my daughter if she knew what was going on. She hadn't even heard the firetrucks. After a little bit the firetrucks left, but all the police cars and the rescue squad were still there. That all happened around midnight. Around 1 am there is a knock on the door. We find out the lady across the street was murdered. This actually was not a huge surprise. The detective was asking if we had seen any strange vehicles in the neighborhood. We told him that we figured she was dealing something, and there were always strange vehicles in the neighborhood.
THe next morning, another detective knocks on the door, asking the same question. We talked to him a little more in depth. We told him we knew she was dealing because of the come and go traffic, people running into her house many times a day, staying for just a minute or 2. He asked why we hadn't called a complaint. I told all the neighbors have, but we were all told the same thing, unless we catch them, there is nothing we can do. We told the detective that we thought she was dealing crack, just by the looks of some of her customers. Found out we were right. I told him, as for strange vehicles, as much traffic as she had, it would have to have been a helicopter landing in the middle of the road.