Come on now, Nigel! Not all who partake fit the stereotypical "forgetful"/slacker image. One of the reasons I recommended Amnesia was because it's clientele (particularly during the day) was much more diverse than some of the dumps over near Centraal or in the Red Light District where it was all foreigners just interested in partying as hard and obnoxiously as they could. At Amnesia for every 1 person with a septum piercing and tattoos, you had about 4 others sitting around in nice suits scrolling through their iPhones and looking like bankers or lawyers - certainly not slacker stoners. What everyone had in common was no one acted like a-holes. They stopped by to have a smoke, enjoy a drink, relax a little and then went about their day. I stayed in the area and this was the same scene day after day.
And Denny, I responded to this question publicly, and the OP very kindly sent me a thank you via private message. So I am sure that they have seen your PM by now and have looked into any recommendations you offered.