i would definately recommend NOT straying off of the touristy main paths (more than 2 blocks off of Revolution Ave) for a man OR woman alone. i commend you're guts to travel to anywhere you darn well please, but like it or not we just should not go some places.
prettyday ~ all of your observations about how americans are viewed is pretty right on. to them, we have everything & they have nothing. they love the gringo's ca$h, but thats about it. because of the lawlessness of some of it's citizens & the corruption of many of the police ~ it can be a very dangerous place. HERE we have laws that we know will protect us from thugs & theives. i live in Los Angeles along with a heavy latino population. in my neighborhood as well as most of the affordable ones, i am in the minority (white). however, i don't find there to be much racial tension between these two cultures. i love the multiculturalism that L.A. has to offer. however we have laws that generally work to keep offending people seperated from the rest. in TJ or any other part of Mexico ~ the laws are not so black & white for everyone. anti americanism is usually very high in some countries & the penalties may be stiffer for gringos than locals.
i don't go to TJ with the party frame of mind. i want to get my meds, do a little shopping, & get the heck back across the border before nightfall. end of story. straying off the main routes because you think you have 'freedom & rights' is not such a good idea. heck, even in parts of my town i feel this way. traveling at LEAST with one other person is definately the way to go.