Sometimes you can tell by the reason the previous project manager gave up the reins to the project. If he left the company against his will, then you can probably assume it will be a mess. If he left for a better job at another company or left the project for one that he was specifically needed on (had a good history with the client or had a skill set that was needed by the new project), then you can likely assume it will be in decent shape when you take it over...