From Nelson Algren's 1955 Paris Review interview:
Read the complete interview.INTERVIEWERDid you ever feel that you should try heroin, in connection with writing a book about users?ALGRENNo. No, I think you can do a thing like that best from a detached position.INTERVIEWERWere you ever put down by any of these [users] as an eavesdropper?ALGRENNo, they were mostly amused by it. Oh, they thought it was a pretty funny way to make a living, but—well, one time, after the book came out, I was sitting in this place, and there were a couple of junkies sitting there, and this one guy was real proud of the book; he was trying to get this other guy to read it, and finally the other guy said he had read it, but be said, “You know it ain’t so, it ain’t like that.” There’s a part in the book where this guy takes a shot, and then he’s talking for about four pages. This guy says, “You know it ain’t like that, a guy takes a fix and he goes on the nod, I mean, you know that.” And the other guy says, “Well, on the other hand, if he really knew what he was talking about, he couldn’t write the book, he’d be out in the can.”
See Pete Anderson's take on The Page 69 Test: The Man With the Golden Arm.