Does Luke 6:30 imply that the person asking has a genuine need?

There was another thread in Mi Yodeya where a Jewish individual played a "prank" on a Christian in order to get his money ($20) since he figured the Christian was obligated to give it to him if he asked, according to his understanding of Luke 6:30 . Needless to say, this Jewish individual, since he admitted it was a "prank," didn't have a genuine need for the money. I have been approached many times by people who were scamming for money. For example, I am approached by a man/ woman outside a grocery store, as many people are. He/ she says, "My truck broke down and I need to call a taxi." I tell him/ her I don't have any money on me, which is the truth. I rarely ever do. I go into the store, and as I walk out, I witness the same individual driving down the street in his/ her car. It was a scam. What were they scamming for? Likely narcotics or alcohol. If I had given this individual money, they would have likely used it to buy narcotics or alcohol. Essentially, I would be contributing to and enabling their lifestyle --- a lifestlye which is by no means beneficial for them. In fact, if they bought narcotics with my money, they could very well overdose and die. A culture of drug abuse didn't exist in the time of Jesus. But, it does today. Hence, my question. Should a Christian indiscriminately give or lend his money (if indeed he has the money on his person) to everyone who asks him? Should a Christian discriminate who and who he does not give his money to? If so, what are some things that could assist a Christian in this situation?