Just a couple of short points if I may.
1) Having spent my entire career in Law Enforcement for a good sized agency and having interaction with many agencies all across the country I have NEVER met a corrupt LEO. Have officers,deputies/troopers made mistakes that cost them their jobs or careers? Yes they have.
2) Professional curtesy to other officers is not a given. I remember giving a ticket to an NYPD because an attitude about being exempt or above the law. It was his attitude that got him the ticket (just as with anyone I ever stopped). I was never a "big on traffic unit" but if faced with an obvious infraction I would work them as necessary and with all the curtesy I was allowed by the driver.
3) Have I ever shown professional curtesy to another officer, yes. We walked in the same dangerous shoes and pursued through the same dangerous streets and gone through the same dangerous doors after people who would take our life with no concern for us or our families.
4) What you say about attitude of officers is a bit misguided. Most (not all) are truly super people. Take them out of uniform and get to know them and you'll probably like what you find. Don't misunderstand what I'm saying. Were their LEO's I didn't care for, yes. Were their ego's, yes. Just don't use too broad of a brush.
Just my observations.
