I did the numbers, such as were available, for Florida once, since the numbers of permits issued, revoked, etc are available as an online public record.
For Florida at least over the last 22 years (since 1987) something like less than 0.2% (that's 0.002 or less) of CCW licenses have been revoked because of criminal conduct by the license holder. No offense to LEOs or anyone else, but if the crime rate among sworn officers was that low over a 20 year period, would there even BE such a thing as Internal Affairs? If the crime rate among police were so low, I wouldn't think a special department just to investigate criminal conduct within the police force would be needed. This obviously doesn't apply to all departments, but there are a number of departments to which this clearly does apply.
There are many examples as people have pointed out of corrupt police forces, Chicago and New Orleans come to mind. A recent newspaper story (last 2 months or so) showed that about 1/3 of all Atlanta police academy graduates had some sort of criminal record, in fact many of them had to settle for working for the Atlanta PD because other departments rejected their employment applications upon doing a background check and uncovering a criminal history.
EDIT to add information
Here is specific info on Florida. Now I recall, that is, you can look at details for each year. I have done this a couple of times over the last couple of years, and it's been pretty similar for the last 2 or 3 years, and I know of no reason why any other year should be much different.
For the year ending Nov 30, 2008: (Nov. 07-Nov. 08)
http://licgweb.doacs.state.fl.us/stats/07012008_06302009_493_annual.html
2017 total investigations conducted involving either a use of the CCW weapon, or a crime/incident of some sort
14 CWPs suspended
123 CWPs revoked
8 put on probation
4 CWP license voluntarily relinquished
TOTAL 149 suspensions, revocations, relinquished
There were also a total of 158 fines imposed. Since these may overlap with the suspensions/revocations above, I won't include them in the numbers.
So how many CWP licensees were there in Florida?
(data from
http://licgweb.doacs.state.fl.us/stats/licensetypecount.html)
As of Nov 30, 2008 there were 531,437 concealed weapon permits. I'll make the assumption that there were this many for the whole year, which isn't exactly true but is an ok approximation for our purposes.
Crime rate among CWP holders in FL is thus 149 / 531437 = 0.00028
So, I misspoke earlier,
the crime rate among FL CWP holders wasn't 0.2%, it was 0.02%.
Ok, so throw in the fines above, we'll assume that the 158 fines were entirely separate violations from the 149 suspensions etc. That's (158+149)/531437 = 0.00057 or 0.06%. Still pretty darned low and as I've explained, the true figure is lower than that since some fines surely are associated with the license revocations/suspensions.
So, I stand by my earlier statement- if the crime rate among sworn LEOs was 0.06 PERCENT per year, would there even be such a thing as a special department called Internal Affairs?
I don't think it's much of a stretch to say FL is representative of other states with shall issue CCW, Florida was simply the first state to begin "shall issue" but now something like 30 or 40 other states do it too. These FACTS dug up from the Florida government records I think clearly demonstrate that a Concealed Weapons Permit ought to be about as close you can get to a "certified good guy" card.
I hope these figures are useful. Good luck, I have not yet met an anti- who has been able to deal with the FACTS but hopefully you'll control your temper better and won't turn off the other person in the discussion.