IMO that stuff is seriously over-dramatized. Yes, you need to use common sense, you don't want to meet a seller in a dark alley at night. However, having bought/sold dozens and dozens of cars and looked at probably a hundred more I've never once had an issue or even a hint of one. You can usually tell in a conversation before hand if someone is straightforward. If they say right off the bat "I'm bringing a gun", the conversation is over (I'm staunchly anti-gun under any circumstance), however I can count on one hand the number of times that's happened. A little common sense goes a long way.
.