Much of the answer to this question depends upon your behavior. Do you plan to stay within the confines of the tourist areas or la Zona and behave as a respectful guest? Or do you get sloppy, fall-down drunk and resemble the "Ugly American" who feels compelled to boss Mexicanos around since he is so much better than they are? The answers to these questions will shape the answer to your question. No matter where you go on this planet, you could always simply be in the wrong place at the wrong time. But if you keep your wits about you, act respectful, and stay fairly sober, you should do fine. Did you plan to cruise la Zona or were you thinking of hooking up with an escort? In either case, best wishes for a grand ol' time in TJ!
P.S. You've been reading a lot about others having bad experiences. Dontcha' jest hate English majors?