There is a difference between the sweet panhandler of lore & the aggressive predator. The latter is more often than not an EDP (emotionally disturbed person) or is a serious user of alcohol/drugs. This group will select 'sheep' out of a crowd for culling- they're looking for a soft mark. Don't get caught in blind areas- corners, construction scaffolding, etc. If you look as if you will put up a good fight, or simply have a 'look' that sends a no-nonsense message- that will scare off most all but the serious nutjobs, they, in turn have nothing to lose & will often attack if they feel challenged. Many/most are armed w/ at least an edged or impact weapon of some sort. There was the incident (Boston I think) where a woman was hit in the head at random w/ a brick by a "homeless" person w/ a history of serious mental illness. I knew a guy who, in Rome kicked a kid in the chest when a group of kids swarmed him & started rifling his pockets & tugging at his camera. He sent the lead kid sprawling the rest took off. We had "homeless" who would cadge money & scrounge food off of the patrons of the outdoor cafes in Heidelberg- the Rathaus (city hall) was right there, cheek-to-jowl on the square- these folks knew they had the legal right to be near/on public property. One guy had the nerve to ask if he could "borrow" a handtruck I was using to move some kegs around. Good for a laugh- Junkies can be funny & clever. Desperate, but funny. I've run many off by simply saying "sorry" & there was no problem, others I've had to knock to the ground. These are not cute, fuzzy bunnies I'm talking about here. Not all are predatory vermin, some are really sad. A quick story: A friend in Berlin had mentioned a woman on the subway who would walk up to you, drop to her knees and moan & wail, pull up her coatsleeve to reveal a horrible, hand-sized ulcerated sore on her arm. She would remain on her knees & wail at you until you gave her money & then she'd move on to someone else. I thought he was kidding- until I was on the U-Bahn in another part of town- sure enough, here she comes & pulled the stunt about 2 seats away from me. Amazing.
Living in Berlin, NYC & etc. you get used to seeing these things- and perhaps I'm a tad hyper-vigilant- but I have NO patience/sympathy for the predatory panhandler, but I'll gladly bring food to those I know to be really down & out & legitimately looking for a meal.