I have a much better solution, one that might cover all of the issues, here.
1. There is always a corpse, but corpses don't always have any consumable meat available. You don't pick up the entire corpse, just the excess meat. For "ordinary" creatures that are large (such as Ogres), this meat would then be automatically cut up into "portions of ogre meat", etc, while smaller creatures (giant rats, goblins) might only produce a single portion. Most creatures would generate at least one portion, but often this will have minimal effect on satiation.
2. Monsters would have an inventory and a set of equipped items. Inventories would be "dropped", which would include typical loot. Equipped items would remain on the corpse, sometimes badly damaged, but sometimes in good condition.
3. Typical equipped items for monsters would be predefined for that monster, and would generally be low quality and weak, with minimal sell value and wouldn't be accepted by gods. For instance, goblins would typically wield a "goblin club", which is little more than a stick. Occasionally, though, a quality item would be generated on a goblin, which you would only be able to find by examining the corpse carefully, with the time being dependent on what you're doing with it. Such a goblin would also be more difficult to beat in a fight, as the equipped item would actually benefit that goblin.
4. Obtaining monster equipment and portions of meat should take time compared with picking up dropped inventories, and should require a separate command. Also, if the PC is "Hungry" or worse, it should be possible to eat directly from a corpse's body (or, if a troll or other creature who wouldn't balk at eating directly from the corpse, unsatiated); but if not hungry, you would have to cut the corpse into portions of meat first. It should also be possible to pick up the entire corpse, as a quicker act than examining it, for later examination (or quick eating, should it be necessary over a longer period).
5. Corpses that in ADoM gave special bonuses (like fire resistance, etc) would instead have a particular portion that gives the bonus. For instance, perhaps it is the eating of a "portion of troll heart" that will give the boost to healing, or a "portion of ogre muscle" that has a chance of boosting Strength. In many cases, it would be a heart or a brain (kobold shaman brain for +1 Ma). Portions that do not have any chance of special effects would simply be called "portion of <monster> meat/flesh". And if the monster died of poison, sickness, etc, then the portions would have a high chance of having that same status (so don't just go eating portions of that goblin you just killed with your poisoned knife - better check first to make sure it's not poisoned).
6. Some meats would be edible when cooked, but carry disease or otherwise be inedible when uncooked. Other meats would be edible in any circumstance, and others would cause problems even if cooked first. And some special portions might have a higher chance of special effects if cooked, while others might have less chance (cooking an ogre muscle would make it more tender, so the possible strength boost would be less likely, but a troll heart might be even better if cooked).
7. Certain notable corpses would have more interesting meats. Flesh golems could perhaps consist of the meats of multiple types of monster, with a chance of some of the portions being special portions (perhaps you could find a troll heart and an ogre muscle amongst the portions). Zombie portions would have a high chance of simply being diseased meat, but a small chance of being healthy meat of some creature. Occasionally a Steel golem would actually leave a piece of metallic flesh, which would be edible under the right conditions.