I read a rather interesting little article once, a part of which touched on the way Tolkien - or rather, his characters - referred to orcs et al. The author felt that there was a direct link between this and the way medieval chroniclers referred to the Mongols. Sweeping out of uncharted lands, laying waste to all they see and taking slaves... yep, I can see where that idea came from. Another intriguing point was that they couldn't be wholly cruel and wicked - given the ease with which they seem to tame wolves and worgs (and boars, wyverns and other assorted beasties for various other portrayals of them) they must have a patient and kind(ish) side - for animals, at least.

In short, the Warhammer approach of making them somewhat stereotypically "lower (under?)-class" English may have something to it - drink vast quantities of alcohol, keep (equivalents of) racing pigeons and fighting dogs and being prone to a spot of football hooliganism when they're on their travels!