Originally Posted by
Shurrikhan
A trash pull and a boss pull, if given equal design weight, are both simply encounters, with the difference that one involves many units and may allow players to prune the capacity of their enemy in an order of their choosing through which units they prioritize, while boss encounters tend to feature just a single unit who may have HP based changes in abilities but rarely outright pruned capacities and therefore will often ramp up in intensity (on-mob-kill mechanics aside) rather than seeming to ramp down.
Trash is trash because its a trash design effort, regardless of whether it has one or many mobs. A well-designed encounter is a well-designed encounter because of the effort and awareness that generated it, regardless of whether it has one mob or many.