The best all around strategy I’ve found (stolen from these forums, actually ;-)) is to only hit the little creeps at night. It reduces the chances of a poison arrow, and once you get close enough, even a low level brother can do pretty well. If they nerf the rotten scumbags, it would be too easy to just steamroll them. Especially when you finally do get brothers like Sarissofoi has!
Thats why they should split them into more sub types. Introduce new ones that even lower level parties can take without stupid amounts of effort (and damage taken) and then keep the current ones as higher tier goblins for which you need the kind of party described above.