I do urban landscape photography and I've done a lot of night shooting. I've been going back and forth between LA County and Salt Lake City for the past six or seven years (yes, SLC is Mormon Town, but it has more than its share of drugs, crazies, and homeless).
Originally Posted by cliveh
I've had one camera stolen, but it was left in my then-girlfriend's unattended car. I've never had anything stolen from my person and I've never been injured, although I have been heckled and yelled at. I know I've been lucky, but I also think that when one crosses over to the wrong side of the tracks, it pays to keep a low profile and to be gentle and polite when approached. Loudly telling somebody to fuck off or calling them names is NEVER a good idea, whether it be a junkie or some jock.
I second what tkamiya said: when visiting a new city, it probably pays to be accompanied by a local. If that's not possible, try to use common sense; if you come across an alley with filthy mattresses and needles scattered about, the danger should be obvious.