In this article from the LA Times, the author describes how teachers leave certain low-performing schools and cannot find jobs elsewhere because of the stigma of being associated with failing schools. It's an interesting two way issue: perhaps principals rightly pass on hiring teachers who were on the faculty of a failed school because they have concerns about their performance. One principal said that despite interviewing many candidates, he did not find any teachers who seemed truly invested in their work. He said all candidates seemed desperate for a job. On the other hand, who's to say those candidates aren't well qualified? Schools don't fail only because of bad teachers. For many teachers, being moved to a more supportive environment where they are given the tools to succeed by their coworkers can make a huge difference.
Before I moved back to New York, I taught in an urban school district in another city. I was told repeatedly by veteran teachers that if I wanted to job in another district in the area, particularly a suburban one, I would probably be better off leaving my experience in the district I worked in and trying to get hired as someone without experience. While I never thought to actually do that, the fact that it seemed to be an advisable practice is something I find shocking.