The industry itself is pretty crappy
Insane amount of competition out there in every market.
Recruiting is a very boring job - you basically call people all day and it get tedious, you also don't use your brain at all or learn anything.
Sales can be very tough.
Most people don't make a lot of money - they don't get to those levels.
Very high turnover
The staffing industry in general is very immoral - you tell people you want to help them find work, but there aren't really any incentives for you to do that. All the vested interest is to find the person who will get hired for a certain position, or just to submit anyone for the spot even if you know they won't get the job.
Everyone in the company treats contractors like children and like garbage. They are nice to them until someone doesn't show up for a day or something - all that matters at the end of the day is the bottom line isn't it. I generally felt pretty dirty working in such an industry.