I'm in the trade and have been for around 5 years now.
I started up a contract recruitment business with some friends after 15 odd years of senior sales in IT and my take is as follows.
Not all recruiters are arseholes just 98% of them.
Most recruiters get into the business because it's a good way for someone unqualified to earn good money.
Most recruiters are under the sort of pressure that would make most people crack and simply don't have time to do what they should in terms of feedback and so forth. In the IT market recruitment is viewed largely as a "numbers" game.
The further up the career ladder you are the better you will be treated, simple economics a 25% fee on a 100k basic is a lot of money, a small percentage on a contractors daily rate on the other hand is not.
The market is saturated with candidates and as such open vacancies are at a premium, be wary of answering questions about where you are interviewing and so on as you are almost certainly being used for leads.
I moved out of IT search into exec search and it's a very different job. People are more open, recruiters tend to be older and perhaps a little less prone to taking shortcuts and most importantly I don't work in competition with other recruiters so if I call someone it's for a genuine job that isn't going to disappear!
I know some very ethical, highly skilled people who are very good at helping people find a better career but I admit in this business they are very few and far between. I like to think I'm on of them!