Yeah, I've definitely had my share of bad people. Generally, the people who approach you to ask for money are usually the ones who are probably scamming / career beggars. One example, I got the same story about needing to make around five quid to get a train home to the next town. I only had about two or 3 quid in loose change, so I took out everything in my pocket to give him. He fished out the big denomination coins and left me holding all the 1p, 2p and 5p coins. Just in 5ps, there was probably 60p there, so clearly he wasn't as desperate for every penny as he claimed, but I was just too shocked by that to even say anything.

A week later, I saw him in a similar spot, this time raising money the get "home" to a different nearby town, and tried approaching me. He obviously didn't recognise me, but also didn't seem at all phased by my somewhat loud "you've got to be expletive kidding me if you think I'm giving you anything else", so he was obviously used to people wising up to him.

There's one guy who's often outside the supermarket I use, I know he must be pretty desperate as he's still there when it's raining really hard, although he obviously doesn't live/sleep in the area. I started just offering him a pack of biscuits or something when I left (I'd buy more because I saw him as I went in), and then started just grabbing a meal deal for him anyway if I saw him there when I went in. After a while, I started asking him as I went in if he was hungry and what he'd like rather than just getting him something random.