No offense and not to start a flame war in the new forum but it is common human psychology to have what is known as confirmation bias. One only seeks out information that is in agreement with your position.
So on technical issues, all political persuasions only quote what agrees with them and do not look for disconfirming evidence.
As far as fraud, etc. - all are equally guilty of such shennigans. It is confirmation bias to declare yourself a member of group A and think only group B does thins.
As far as doing it for a good cause - if one looks at a strongly held ideological belief - pro-Rutabagas or ant-Rutabaga - the zealots think that position is for a good cause and act accordingly.
A good read is Terror in the Name of God that examines how folks who propose to follow the tenets of various religions that preach all kinds of nice things - become monstrous killers.
Also, don't forget that many politicos do what they do for sheer self-interest - they have little real beliefs beyond their own venial desires and need for success. They take ideological positions to hoodwink their disciples into following and supporting them.
How to break this? People need training in empirical methods to rationally examine positions on the basis of the merits of the issue. Many folks don't - they are socialized to the emotional, playing on fears and the like.
They are taught to be self-centered and anti-intellectual. If we could break that - we would be in business. One can read many books on the areas of logic and thinking that people engage in. Training in such flaws would be useful.
So examine yourself and say - did you look at both sides of the issue? Are you overemphasizing one incident to the exclusion of the whole picture?
If we move away from guns and 'our' opposition - you would find that the correlated groups are just as irrational on many issues as you may think 'our' opposition is on guns.
Hope, I wasn't too political or shying away from our mandate. If the purpose was to say that political position A is a paragon of decision making rationalilty as compared to B on all things - I don't buy it.