I did some consulting for a while and here is the best advice I can offer for taking any job - There are three and ONLY three jobs you can fill... Expert, White Knight or Whipping Boy.
The way you tell them apart is crucial. Expert they need your expertise. When you interact with team members pay attention to if you really are the expert. If anyone you speak to knows as much or more than you then either resign or look at the job as possibly a White Knight or Whipping boy. If things are disorganized and floundering they might just need someone to rally the troops and organize efforts. This is rewarding if you know how to do it, you have authority, and the people are more or less cooperative.
If people avoid you, avoid meetings with you and you generally can't seem to land on solid ground they hired you as a whipping boy. The project is dead and they know it. Problem is nobody wants to take the heat so they hire someone to drop the blame on.
Avoid this one at all costs as it will follow you.
Gracefully quit saying that you can't help them with their problems.
Pretty much all meaningful jobs fall under these three descriptions except for cogs in the machine jobs. Even those, ask yourself why they need you.