I like this post from the Agile Executive called, Top 10 Reasons for Project Success.
Evaluate a current project, or one that’s about to begin. Concerned? don’t be afraid to call the "time out" sign and do what’s needed to either get the project moving in the right direction or kill it.
There are many projects that ought to be killed, but we lack the courage to be the one to say – this is not the right use of our time and resources. Or, this project does not have the support and involvement it needs, so let’s put it off until we have both.