Over the past few years, I've been accused of playing favorites with the rogue specs. During Wrath, I was characterized more than once as the ArP-mongering combat rogue who neglected Mutilate builds. In Cataclysm, I'm supposedly the devoted assassin who never gives combat or subtlety a fair shake. The truth is that I don't care what spec I'm playing, and I'll play whatever gives me the best results.
I played Mut/Prep, HARP, and even pure subtlety in the arena during The Burning Crusade. I've raided extensively as both combat and assassination, and I've leveled my rogues (plural) with each of the three specs, as well. I frequently swap specs. I love combat for solo PVE play, while subtlety holds a special place in my heart for ganking and world PVP. I currently raid as assassination simply because it's how I get the best results. I'm not alone in this philosophy, as most rogues will do whatever it takes, including a respec, to get the most out of their characters.