The mistake I see __consistently__ is that when I'm discussing an opportunity / relationship with someone who is "hiring" is that they don't realize I'm interviewing them as well. Fairly often, those who don't realize this are the same ones who will hint / complain about retention and such. They want better people but that have no idea how better people think / feel and how their approach will never get them the type of people they need.

Once I interviewed at a large fashion company for a Python programmer position. I asked to see IT offices (no way, even if I had required a second interview expressly to see them; the building layout suggested some sort of overcrowded basement), I asked about salary (matching my current one would have been a stretch), about benefits like a car (oh no, only for top management!), about training (studying their software after hours, on my own time), about lunch (internal mess hall only, and nobody can leave), about their software engineering approach (overtime, and proud of it). They unconsciously went out of their way to demonstrate a corporate culture of paranoid secrecy and to show that IT had very little consideration within the company. I tried hard to find a reason to like them, and when I found none and refused their offer I got an angry call from the manager: I wasn't "motivated". He thought I had wasted their time.