This is probably wise advice. We got it the WHOLE way through California, and especially as we got down further South. For us though, getting shot/stabbed/robbed was the least of our concern. We had been putting our lives in our hands the whole trip.

In Alaska and Canada, we were at high risk of getting randomly murdered apparently; We saw dozens of billboards that warned against hitch-hiking because of a string of killings. Then there is British Columbia which claims to have one of the highest populations of brown and black bear in the World. Should I even mention angry moose? I'm not sure what the risk was with them.

Then there is the fact that you have nothing between you, and the asphalt/trucks/cars/RVs except for a layer of spandex. One little mistake or bike mal****ion at 40 MPH, and you are hamburger, ya know?

By the time we got to TJ, we had so much behind us, and that was the end of our adventure, and like I said, getting shot/stabbed/robbed was a legitimate possibility, but we did not fear it.

GRANTED... having said all of that, we don't venture beyond that touristy shopping area directly accross the border and I also have my can of bear mace holstered. We have made several friends in the shops down there, and if you know what you are looking for, you can spot the "bouncers." These guys' shops rely on US tourism, and if people are getting killed or injured all the time, its just bad for business, so there is this sort of mafia style security in those areas.

As far as venturing into the heart of the city however... You said it, you are tempting fate.