I saw a guy in my city checking every nook and cranny he passed and he looked well practised in the likely spots. Quite interesting to see him at work and the places that got extra attention: the most keen search was around the frame of a sign, the second rank were the larger crevices in brickwork and around utility pipework.

I assumed he was looking for other addicts stashes e.g. maybe they stash what they're holding when they beg to avoid losing it to police searches? Maybe it was dead drops but it seemed like a street thing rather than a darknet thing but what do I know...

I don't know if he was successful or just nuts but given I've found full baggies just laying on the pavement, maybe it's not so hard.