BTW, when our tour was in St. Petersburg in 1992, I was very tempted to walk down Nevsky Prospect and check out the Gostinny Dvor facade. Unfortunately, the number of "shady looking" characters meandering around and giving us dark, sidelong glances prevented me from doing so, especially since nobody else in my tour wanted to risk their pocketbooks and/or lives and accompany me! 
The unsavory characters were at the front of Gostiny Dvor for one of a number of reasons: using the Metro entrance under Gostiny Dvor, waiting for the many buses that stop in front (Nesky Prospekt) of Gostiny Dvor, waiting for a trolley to stop in front or on the side (Sadovaya Ulitsa) of the building, and the reason that came to your mind, robbery, theft, pick pocketing, selling drugs etc.
In fact I recall a friend of mine relating to me that I should never use the street to the rear of the building, Ulitsa Lomonsova, or the other side street, Dumskaya Ulitsa, because a friend of his was robbed and stabbed to death near where Dumskaya meets Lomonosova.
Once one gets by the outdoor characters, one only has to watch out for pick pockets. I recall going to Gostiny Dvor many dozens of times to purchase snacks, groceries and once to buy new bed sheets without ever a single incident.
DAP
