Uuuuh I don’t think any maid cafes are open past 11 pm. O_O None that I’ve heard of, anyway. You might be thinking of girls bars or kyabakura.
But yeah, new customers can be the scariest, really. > 3< The regular customers are usually really nice and really want to support the cafe and the waitresses. With new customers, you never really know. Some become regulars, while others just go there once when they’re already drunk for laughs and pick on the waitresses. I only remember one incident where we had to actually tell a group to leave, though. Most Japanese are more polite and reserved (at least in public, lol).
For the most part, I don’t think people go to maid cafes to get drunk. Most places sell alcohol and a lot of people might get tipsy, but I don’t think most people go to maid cafes with the intent of getting blackout drunk. It’s a really fun job, and I felt really safe where I was. The other girls always had my back. ^^
There are some maid cafes that are open past 11 pm. ^-^ I don’t know all of them, but for example Crown Tiara in Akihabara and the maidreamin Shinjuku, Shibuya and Ikebukuro store are open until 5 AM on Fridays and Saturdays. ヾ(＠＾(∞)＾＠)ノ