For us, a project's results were deemed acceptable when the following criteria were met:
To some, these requirements may seem incredibly, if not dangerously, lax. To us, they permit a fantastic degree of freedom when it comes to declaring success. Considering these criteria, and perhaps omitting a few here or there, I would say without a shadow of a doubt we experienced a near 60% success rate. Meaning that for every 10 projects we would have ever considered, 6 didn't kill us.
For more information, see our page on project standards.