The drunk ones are usually the ones that suck in some way. Across the street from the motel I work at, there's a restaurant with a fairly large bar in it so when night comes, some of the locals will go wandering looking for a cheap place to crash for the night. Unfortunately, they usually choose us to come to since we're right across the street from it. There's another bar just down the street so sometimes those ones come to us as well.
The mellow ones aren't too terrible, they're pretty tolerable and only slightly annoying. It's the ones that are so fucked up drunk that they can't even speak clearly that like to cause trouble when things don't go how they want to. Usually when they come in, it ends with them making sexual comments about me or threatening me. Most of them leave pretty quickly when I threaten to get the cops involved. But some of them won't take no for an answer and will continue harassing me until I'm forced to actually call the cops.
There was one time I remember that I had rented a woman a room for a lower price than our usual rates out of sympathy because she got me with the whole "I'm homeless" thing. She came in later, screaming at me for really no reason and threatening to sic her boyfriend on me if I didn't start being a "proper employee". She also had the nerve to start yelling at me because she thought I was a prostitute. She eventually got escorted out by an officer when I got tired of dealing with her. I don't think she was a drunk one though, just a jerk. I really despise it when people like that decide to take advantage of another person's kindness. I gave her sympathy and she repaid me by threatening to get her boyfriend to kick my ass.
There's also been quite a few customers who have yelled at me because the motel doesn't have room service. People from other States and countries automatically assume that just because we're close to San Francisco, we'll have room service. They only wish they were staying at a motel as classy at that. When they find out we don't, they yell at me like it's my fault we don't have room service.