I have found the crowds at the 9:30 club for the most part to be polite and well-behaved, and not excessively drunk. Most people come to hear the bands not go crazy. Of course, they are some harder heavier bands that may attract a rowdier audience, but if you have a more mellow taste in music it probably won't be a problem. The 9:30 club is more like a concert hall than a stereotypical nightclub. I have found crowds at the dj dance clubs that go on later into the night to much rowdier and more into the crazy alcohol drug, and hitting on people behavior than the audiences at the 9:30 Club. The 9:30 club crowd is more about enjoying the music.