Many of the homeless are un-(or under-)treated mentally ill. I know that doesn't help your problem, but maybe it will help you understand why they do what they do. It's not always out of laziness or disrespect. Being a "decent goddamned human being" can be quite difficult for some.
Jam, I very much agree with your entire post. (except for one small detail: I used to work with psychiatric patients, and I know first hand that mental illness can sometimes present in the ways that Anon described.)
My only point was that I think people sometimes forget that the homeless have a higher percentage of mentally ill individuals than the rest of the population. It is by no means all of them, and some of them are just assholes, but the difference is significant enough that one should keep it in mind when dealing with them.
Like any other group of people, a significant percentage of homeless people are assholes. There may not be any changing that...
Well, my motto is "housing first". I tend to get bitchy when I'm cold and unwashed. But I also report shit. You know how it goes.
My only point was that I think people sometimes forget that the homeless have a higher percentage of mentally ill individuals than the rest of the population. It is by no means all of them, and some of them are just assholes, but the difference is significant enough that one should keep it in mind when dealing with them.