II all depends on the situation. We were recently in Rome and, near the Castel Sant'Angelo, there was a young man beating his heart out on collection of plastic and metal containers. He had a nicely-made sign in three languages announcing that he was saving to buy a real drum kit. We and other tourists thought it was amusing. The vendors who were set up near him for the day must have been ready to kill.
In Cartagena there was an older Asian man playing a Chinese string instrument. We each gave him a Euro because he reminded of a similar musician who used to set up shop near a book store in our neighborhood. He also wasn't loud enough to be a problem and the cultural disconnect was slightly surreal.
I do dislike the 'captive audience' performers who haunt NYC subway trains. These folks depend on
being so annoying that people will give them money to go away.