Usually just small things, with coworkers and how long they'll last. We get contractors that come into our group every so often when a need arises. Unfortunately, it's hard for contractors to get hired on full time unless they get lucky and a FT position opens up. It takes weeks/months for someone to get good at the job we do, even just understanding the full process takes awhile for someone to get their head around. You can usually tell pretty early on how quickly somebody is catching on and whether they're going to make it.

There's some people that come along who are extremely talented, charming, and/or intelligent that I know would be an absolute perfect fit for our group, 99% of the time those people will just find a job somewhere else. They're great workers and they're not going to wait around if another opportunity comes, which they're usually smart/connected/talented enough to see plenty of opportunities come up. The other, unqualified people who we sometimes get stuck with, inevitably make some sort of simple, yet expensive error that gets them let go. It's like seeing an easily predictable scenario, but being powerless to do anything about it.