I couldn't find the above quote, TB, but I think the beginning of Chapter 11, Book 1, painted a contrary picture of McCluskey, that of an "honest" dis-honest cop.

"He had been a good cop, a brave cop....he was a very tough cop and a very fair one. He never...goofed off...always made his rounds...gave his stores (on his beat) a lot of protection, a lot of service...He also obeyed the system...he would never make trouble to get an extra payoff for himself...he was content with his share of the station house bag...he never tried to make extras...he was a fair cop who took only clean graft."

When Sollozzo offered him $10,000 to leave Don C. unprotected at the hospital, "he took the money in advance, and did the job. When he recieved a call from Sollozzo that there were still two of Corleone's men in front of the hospital, he had flown into a rage... being a man of principle, he would have to give back the ten grand."

Sounds like a real honorable and trustworthy guy to me