Unfortunately all the ads and giant billboards tell the muggers that it's that time of the the year for mugging so they tend to look for folks who "don't fit in".

Generally, I recommend taking a taxi between the hotel one is staying at and the convention center and not walking around at night, taking one of those leisurely after dinner strolls.

The "lost tourist with the backpack and a map" is also a bad way to broadcast oneself as a potential victim.  It's generally a good idea to try to get one's bearing's at the hotel (or the convention center).  At worst, just get a cab to take you to where you need to go.

It's not that it's actually *that* dangerous, but one definitely has to be cautious.

Having lived in San Fran - I understand the economic disparity of the haves and have nots. Most of the violence I've seen involves homeless beating up other homeless. Still, my car has been broken in a few times on Van Ness + Market (the edge of Tenderloin).