I've seen this happen kind of in reverse.
Group of us went to a regular field that gets a lot of wide-ranging traffic. Lot of first-timers, and a lot of higher-end players. Refs split a crowd of us into two largish groups and I noticed a tiny group of phantom-toters who were wearing just basic stuff, jeans, BDUs, etc., but who looked all wrong. They stood wrong, acted wrong, everything was wrong. And by 'wrong' I mean, 'looked like they knew their business.'
Some of the other folk in our large group (none of my crew) started laughing at them and saying things like, "What are those, pumps? They don't even have hoppers! Boy, are they going to get spanked."
I politely suggested, shortly before the whistle, that probably that little group shouldn't be underestimated, even if they did have 'goofy old guns.'
Turns out I was right, and those three or four pumpers did a lot of damage to the very folk who were laughing at them.
Thought it was hilarious, and said as much to them after the game.