Actually, that isn't quite true.

If you look at Eminence (the #1 guild in WoW full stop), they have two Warriors in particular, World and Paytun, who are far more buff than anyone else (both wield Thunderfury and all their other items are all epics from MC, Ony, BWL or 4 Dragons). It has nothing to do with attendance. It's because they are the main tanks so therefore they get preference regardless.

In my guild though, it is attendance based. Since I've been to 27 consecutive raids and I make a load of potions/farm a lot of Black Lotus for the guild, lately I've been given my Cenarion pieces over those with equal attendance but they've been far longer in the guild compared to me.

And Raz, 'slacker' usually means they're at work. At least for my guild, anyway.