If I was a criminal, threat from CCWers would not bother me. Since the notion of More CCW = Less crimes assumes the bad guys have a running knowledge of CCW data, then they would have a running knowledge that of the CCW folks in a given state likely don't average more than 4% of adults. A couple of states are a bit more, but most are quite a bit less. So they know that at any given time, probably 80% of those with CCWs aren't carrying. There are all sorts of reasons folks don't carry and the schooled bad guys must know the data, right? Some are lazy. Some only carry when they are going some place dangerous. Some only have the CCW for if they ever decide to carry. A tremendous number of folks can't carry at work and so don't travel with a gun to and from work, sometimes because they can't even have a gun on property (specific states). The criminal element will also know that of those folks with CCWs, many will not respond unless directly threatened and if taken by surprise and directly threatened, won't respond at all.
So as a bad guy, I figure I have a 99% chance or maybe better of NOT encountering an armed CCW holder, and likely better chances of that when it comes to encountering one who is willing to respond. So, so long as I stay away from people's homes where home ownership of guns is tremendously higher than CCW rates, stay away from carjackings where folks are apt to carry guns in cars, I can nearly totally negate the risk to myself of encountering a legal CCW holder who is willing and capable to act.
Okay, let's face it. Criminals that think that much are not the criminals committing most of the crimes. CCW does not stop the junkies from needing their fixes who turn to crime to do so. CCW does not stop child molesters from desiring children. CCW does not stop mentally debilitated people who do crimes from being any less debilitated to reason away doing crime....etc.
I found this interesting. CCW does not lower domestic violence numbers. Here are some stats from Texas from 2001-2008. While the number of Texas CHLs increases annually, so does domestic abuse.
If you look at city data, some of the highest concentrations of CCW holders are in locations that have some of the highest rates (depending on year) of violent crimes such as Dallas, Houston, San Antonio, New Orleans, Memphis, Atlanta, Miami, etc. If CCW was supposed to bring the rate down, this then pattern should not occur.
To date, CCW cannot be shown to affect the rate of crime, violent crime, murder, etc. It can definitely have a very significant and game changing impact on any given crime where lethal force or threat of lethal force is warranted and necessary.