Actually this would make for an excellent cleanup mechanism.
Side view of entrance / killing field
B:_..FWWW <-- cross section of entrance
XB_X <-- 1 z-level below
.......... <- sorting area
X = wall
B = burning bins
: = wall grate
_ = hatch cover
. = floor
F = floodgate
W = water
Kill gobbos in the killing field, when clear, open floodgate to wash gobbo bits toward bin which evaporates water maintaining a constant water gradient from the source. When everything is washed over close floodgate, bins empty hallway of water, open hatch and drop everything one level down where the next bin incinerates all of the organic bits. When they're burned up, open that hatch and dump the armor and weapons into the sorting area.
You could make this area as long as you wanted and with some clever engineering, get a water gradient set up to push down the length of the hallway as the first step to shove all the junk into one corner for dump/incinerate - sortof like those two-step car crushers that work lengthwise, stop, then work cross-wise.
[Edit] Trolls would be a problem since they'd toss the floodgates and then you've got real trouble, so you'd need to have a means of dealing with them or change the setup some so that perhaps the water is held back by a drawbridge that when down covers a channel that the trolls can't reach over.