It’s very unfortunate, but probably for every legitimate request for tzedakah, there are several that are just doing “shtick”. One solution has been various Vaads maintaining a database of tzedakah collectors who they know to be legit. So, when someone rings the bell, I ask to see their hashkama from the Vaad. And also, I will not open the door to a strange man if no one else is home.
Those of us who live in frum neighborhoods also know that there is a virtual parade of pushka shakers on Fridays. How many of them are probably not even Jewish?