I lived and worked in Baltimore (and DC) for several years. Thank goodness I'm in the burbs now but I digress.
I went to the bars frequently and I observed. I can tell you that on a weekend night there will be a guy or several with coke, heroin, pills, and speed. He will be socializing with friends, he will look normal, he will know the bartenders and waiters, he will be the guy who everyone knows his name, he will be charismatic and cool. He will also be on his phone frequently and he will also slip in and out of corners and bathrooms, or step outside around the corner to meet people.
I knew exactly who these people were and what they were doing. And I am not pleased to say that some people I knew bought drugs from them. It is like this in every college town and every area with a bar scene.
After the bar people go to the afterparty at someone's house and even more drugs are consumed into the wee hours of the night. You will see people from all walks of life. And especially in college towns and big cities it will be a mixture of rich and poor, black and white, gay and straight, jocks and hipsters, all partying and getting high together.
Just my 2 cents.
I could go into any bar in Baltimore this weekend and within minutes know who has the drugs.