^They're just worried about getting busted by the cops while standing on the street selling dope, and being able to get rid of the dope quickly while still being able to get it back later if they needed to.
I also wated to address this fear that the uninitiated have of copping on the street. The first time you go to do it, it's terrifying and you worry about all the things everyone is asking about(who to ask, getting robbed, getting ripped, getting busted, etc...) you get over pretty quickly once you've done it once or twice. After a while, it becomes almost second nature. As far as first timers worried about who to ask, if you go to the right area this will be a complete non issue. It will either be painfully obvious, or you will be approached. You will probably look and feel extremely out of place, and guess what, you are. Everyone who sees you knows exactly why you're there, and if they're able to help you, as long as you don't look like a cop, you will be offered drugs, people may eve be fighting over your business. They want to get rid of their dope for the day so they an "knock off work," and go smoke a blunt and drink a forty or whatever as much as you want to buy the drugs from them.
It's big business, no real dope spot wants its reputation ruined by having people getting ripped off there. After doing it a few times, you'll know who to avoid and probably even have some idea of where the better shit is. You should probably worry more about being busted than robbed, the people from the neighborhood know why you're there, but so do the cops. Just use common sense, and as everyones else said, always follow your first instinct, it is usually right. And Be Careful, no matter what I say it's still fucking dangerous.
jr0k
btw the worst for me never had anything to do with worrying about being robbed or even busted, it was having to look in the eyes of the regular working folk who were there just going about their daily business. They know why you're there too. They know all too well and sometimes the look in the eyes of some of those young mothers, old men on the way back from the night shift at the factory, or old women who had never been given a thing in their lives was almost more than I could bear(never actually more, the only thing I really couldn't bear at the time was the thought of not being able to get any more dope), I felt really fucking selfish, almost as if I were to blame for all the problems in their lives. Getting the dope in my hands and then as quickly as possible into my body was the only cure for that(and a damn good one too, at least temporarily).