People always seem to disregard how dirty Calzaghe actually was in that fight.
He was throwing low blows and rabbit punches throughout the whole fight. He even admitted to hitting Hopkins low in the 2nd round because he got knocked down.
Calzaghe Says Low Blow Against Hopkins Deliberate!!! on Boxing Daily
Hopkins was dirty but Calzaghe was no better.
This fight had no clear winner, Calzaghe was sloppy and inaccurate and Hopkins was over cautious. You either had Hopkins winning because he landed the cleaner harder punches or you had Calzaghe winning because he threw more and controlled the tempo.
I can agree with majority favoring Calzaghe because he controlled the tempo of the right later on, but it wasn't a clear win.