CNN Money has an interesting slideshow in which debt collectors talk about their experiences. I'd agree with what one of the last people says: the whole industry needs reform.
When I started my own collection agency and we had our first big customer, I needed to hire 30 collectors. I posted one job opening and had 400 to 500 people apply. As soon as I told them we did drug screening and background checks, the pool went to less than a hundred people. This just shows how much the industry needs to change.
The fact is, collecting money from those who owe it is a miserable job. That means that the people who do it are going to be miserable--and that it's probably hard to attract high quality workers.
Pair that with the fact that the debt collectors get abused by the less reputable debtors (or those who are simply at the end of their rope), and the fact that people being collected upon are disproportionately uneducated people who don't know their rights, and you have a recipe for disaster.
I'm not sure I have any very good solution, except for making sure that old debts actually die. But it's something we should spend more time thinking about--only we don't, because the people who suffer the most are the least politically powerful.