I'd never really given this issue much thought, but I will say one thing: If you do PMs, and drive home late at night through areas that are heavily populated by the local constabulatory types, the shoulder boards just might help you avoid a ticket when pulled over for minor infractions!
I can honestly say that, in the last 10 years, on 2 occasions, I would have (should have!) gotten speeding tickets had I thought to remove my boards and ID for the drive home......... Both times it was basically "take it slower Capt., have a nice night." and off I went! I now just remove my tie, and leave the boards and ID on. If I stop somewhere public on the way home (a rare occurrence), I'll pull them off.
I drive a sporty, loud, domestic rwd V-8 powered car to and from the airport, which seems to catch the cop's attention even when I am not breaking any laws (I haven't had a ticket in over 10 years). I get pulled over several times a year, for no reason other than being in their jurisdiction at 0200. As soon as they see who's driving after pulling me over, they usually make up some lame excuse like a tag light out or something and send me on my way.
FWIW, I drive through a bunch of rural, central FL towns (each with their own "Barney Fifes" with radar and little to do) between MCO and APF in the wee hours of the morning.
IMHO, walking around a mall in full regalia is definitely on the "dorky" side, but who am I to judge!