Does shoes hanging over a telephone wire mean that crack is being sold?

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I read in a local magazine that was talking about a very poor area of a local large city and it said just that. (that it is sold in that particular area) I was rather shocked because as we travel around our city on errands, I have commented to my daughters on how funny it looks. Is this what it really means? Am I being a naive mommy? Can anyone enlighten me on this?