If you would use daemontools or similar, you would never have any stale PID files. Simply because you don't need any PID files. (To be honest, PID files are a stupid idea, as you will see when you understand how clean deamontools work.)

See Re: Daemon::Control pid-files and the postings linked from there for details. See Re: How to get the process Id for why PID files are stupid.

Alexander