In my home study lab, I'm finding that the 'ip accounting precedence output' and 'show int e0/0 precedence' commands do not work as expected when the same router is the one generated the traffic you're hoping to capture.
What I was doing was using a policy-map to set the IP Precedence to 5 of generated ping packets and the 'show policy-map int e0/0' command showed that these markings were being set. However, the 'show int e0/0 precedence' output showed this traffic as precedence 0 instead of 5. So, although I can't find this written anywhere, it appears that if the capturing and generating router are the same, the show output won't have show the markings on the packets. This is what I'm gathering from my experiments. Can anyone comment or corroborate that?