[the guy who be short]

Orcs are extremely salty.

Notice that whenever a mound of dead orcs is created, grass ceases to grow above it. It is quite obvious this is due to extreme saltiness in the orcs' blood levels.

Now, orcs were tortured and disformed Elves. It is now apparent that the fashion is which Morgoth tortured them was to create open wounds and then rub salt into them. Eventually, this salt was assimilated into the Orcs' bloodstream, resulting in salty Orcses.

This explains their disgusting taste - poor food for Shelob. They taste like extremely salty pork.