I didn't read where someone said all of Amsterdam is a cess pool. There are some very nice sections. But to imply it is almost "drug free" is a very significant overstatement. You see a lot of lost souls in the main area of town.
I remember being there in the early 70's during the drug revolution. I had a movie camera and tried to take a picture of all of the druggies on Dam Square around the statute. There were hundreds. They had postitioned one druggie on each corner of the statute and they had mirrors to flash into your camera to prevent pictures/movies, etc. The city is still a haven for this as it was open in the 60's and 70's and many have stayed there. Of course a great many were avoiding the draft and could have protection from it. The
parks were dens of drug users, open living, etc.
The city has never lived down this reputation and thats why many still flock to Amsterdam. We were there a year ago and did not feel threatened. Liked the city but did notice a number of drug users both young and oldies.