I play SP, and last nite I Mat'ed my blizz sorc, so I tried to do some cow runs because I read that hell cows can drop IK and Tal armors where Meph can not. I made a lot of steaks last nite, but nothing good dropped (on /player5). Most items dropped were white...
I know that MF is luck and all, so I'm ok with it so far, but I was just curious about how other people's experience is regarding MFing using hell cows.
BTW a lot of runs and flawless dropped. I even got 2 Sols last nite, and I got 2 monarchs that I can socket for spirit if I want
Cows don't drop more uniques than other monsters. It's just that they appear en masse on a wide, open field, move slowly, have low resists and no missile attacks, so they are rather easy to kill if you can deal enough damage. They are quite good at dropping jewels, charms, gems and nonmagical items.
If you are looking for unique and set items which Meph can't drop, go into L85 areas (Pits, Ancient Tunnels, River of Flame, CS, WSK and others) and hunt bosses. If you are looking for uniques which Meph can drop, visit Meph
Of course you can optimize cows a bit. Occasionally I would start a new game right after killing the king --- since the king also tends to have some bosses around, and the red portal often seems to spawn very close to him, this was some form of "speed cowing" :-)
At other times, I would clear out the whole map.
At one time, I needed a polearm for Insight. Went to the pits 2 or three times, with no result. Got bored and decided to do cows instead --- got one on the first attempt.
Of course there was luck involved, but... there ARE a lot of monsters in the cow map. On the other hand, I do get a bit worried with multiple bosses close enough to share their auras... this can easily cause quadrazillions of cows running around with multiple auras under their feet. But it looks more dangerous than it really is...