I think that's the danger of confusing the real world with the movies. In movies, you can do that safely. Of course, you can also smash a car window with your fist without breaking your hand. In real life, if you tried that she would run from your apartment and think you were a major sicko. Also, it would be a very real health risk. The bacteria h. pylori, a key cause of ulcers, could definitely be spread this way. The lower GI (gastrointestinal tract) contains all sorts of bacteria that are very damaging to the upper GI. The lower bowel is designed to contain all sorts of bacteria safely. In fact, it's necessary for proper digestion. However, those bacteria can be deadly if introduced into other parts of the body. The nightmare scenario would be that lower GI bacteria introduced into a very small cut or sore in the mouth could lead to septicemia, a potentially life-threatening blood infection. That is why some armies spread human or animal feces on spikes in booby traps; to make an otherwise non-life-threatening wound life threatening.
Moving on to the behavioral side, let's face it; real women just don't act like they do in the movies. Or, if they do, it's because they've seen the movies and think that's the way they're supposed to act. This link addresses that issue with a little humor.
http://treebeard31.wordpress.com/2007/08/25/things-i-learned-from-movies/