WOW - Confirmed: Loot is not random : World of Warcraft General Discussions

Thundgot replies to the questions, "So why do class set items drop when that class isn't present in the instance?"...

The end result is that people are taking the assumptions way too far. :p

Of course there are rules concerning loot. You won't find a level 10 random mob dropping the same loot as Illidan. Edwin VanCleef drops stuff no other mob drops - not even randomly from level 70 mobs outdoors. Some mobs can drop cloth, others not. Etc, etc.

That does not mean the characters involved, the time of day, the guild, the raid leader, whether it's raining in Shanghai or the colour of your bicycle has any effect on the drop. It might be a factor in a computer generated "random" seed, but as long as it's not the only factor for the seed it's completely irrelevant what the factors are - it's as random as it gets.

And the stories of streaks of good or bad luck on drops only confirm the randomness. Between the thousands of guilds and groups doing the instances there has to be one, or ten or fifty or even hundreds, who get the same item(s) (almost) every time. But if everybody got that, we'd see nothing else on the forums I'm sure.

Thanks