I know a few police officers, too, and I would agree with this, plus one is overly fond of the "kh^nt" word.
(Pardon me - it's the most horrible word and I hate to use it.)
I think in a stressful environment like that, it is a way of dissipating tension and then you just get into the way of it.
The only people I have known who swear worse/more were the privately educated lasses I met at uni.