We recently had a vendor plug a server into an interface set to port-mode access on one of our EX4200 switches and complain that they couldn't get a connection. After spending an inordinate amount of time looking at the switch config and cables someone finally noticed they were tagging on the server. Removing that fixed the problem.
My question: is there any command we should have run that would have told us that there was a trunk plugged into an access port? I've been searching around and haven't found a good way to troubleshoot this issue other than don't configure it that way to begin with (duh).
show interface extensive didn't show anything immediately indicating a problem other than no traffic passing.