The free young american pussy to be had in TJ is pretty much for the young guys (18-30). In college me and my buddies got our share of stumbling drunk party girls in TJ. Not the best sex, but great when you are young, broke, and horny. If you are over 30 years old, you will stand out like a sore thumb trying to make moves on these 18-22 year old girls. They will likely react as if their dad's best friend just make a pass at them "eew...I think he was coming on to me..."
If you are under 30, go for it- you have great odds of scoring some pussy for the cost of a few tequila shots and the headaches of putting up with a horny drunk party chick for a few hours. Oh yeah, get a room on the Mexico side of the border- it will help a lot they often have had too much time to think about it and also start to sober up and bail on you at the border. Get a room at the Nelson- it is damn near walking distance from most of the bars on Revolution and a short cab ride from many others.