min maxing is a type of competitiveness some people really like doing. As for me, I am a bit of an OCD min/maxer.
When I single box my prot warrior, I am min maxing my tanking gear for best mitigation or best tps or highest hp. depends on what I'm doing. I also religiously check the EJ forums for the latest theory craft.

When it comes to other characters I min max the highest possibly profitability rate for my characters. Almost every single one of my alts have some sort of profit reason for me to level them. I rarely if ever level a character that doesn't benefit me in the financial sector of world of warcraft.