Comments posted to our Dark Souls 2 Wiki
Item discovery is like a giant wheel of fortune.

There are 10,000 possible spots on the wheel for the needle to land, and each item the enemy drops gets its own little wedge.
You only get an item if the needle stops on that wedge, if it stops on a blank space you get nothing.

These wedges are a default size + the size of your item discovery, so putting on item discovery gear or crushing a coin always increases your chance to get what you want - it makes all wedges bigger and only makes the blank space smaller.

Not all item discovery sources stack, though. Prisoner's Tatters doesn't stack with helmets except for the Prisoner's Cloak, using more than one Rusted Coin is worse than just one.
Best gear is Gold Serpent Ring, one Rusted Coin, Mimic Head (Jester's Cap is you don't like the HP loss), and Watch Dragon Parma. This will only about double your chances of getting items though, so it isn't really worth it to go out of your way to get all 4 if you already have 2-3.
It says here that killing an enemy over and over will decrease it's "chances" do drop something from it's drop table. Is this hidden decrease nullified if i'm in the company of champions?
Actually, this is controlled by a demon within the game's code; said demon will read your mind when you are about to farm (getting unexpected item drops don't count since you are not interested or thinking about it) and it will erase a desired item from the drop list. Want that cool sword worn by X enemy? you'll only get helmets, shields, a comically large quantity of trash... but not your desired sword

Trust me, my dad works for From
If you don't have enough stats for the Jester's Cap (like less dexterity than it requires), do you still get the item discovery bonus?
Probably. As it’s a hidden stat it’s hard to know for sure.

However, I believe stat requirements are for the weapon’s melee attack and defence bonuses. For example, look at the Dragon Tooth, which has has a 50 strength requirement, you can still get a +50 fire defence bonus even though you don’t meet the stat requirements. This is not a hidden stat, so you can see the +50 increase in your fire defence stat when you haveit in either hand (usually off-hand, two-hand your primary weapon).
You do, its just like with Jester gloves. Only if they break you stop getting the effect, and if your stats arent enough then the item stats are reduced until u reach the requirement, just like with weapons.
Having Item Discovery has a HIDDEN stat is fucing dumb FROMSOFT
a little tip on farming (SOFTS PC).
- this happened to me during dragon scale farming at imperfect lair. I'm using lightning greatsword+10 + sunlight blade + farming gears. During farming, when nothing dropped from imperfects after some time (5-6 imperfects in a row), I changed my weapon to powerstancing dark large club+10 & lightning greatsword+10, the first imperfect i kill with these weapons drop a scale & after a while not getting any drop as before, I changed back to 2h greatsword & i got scale from the first kill. same thing happened when farming at dragon shrine, it seems, drop rate depends on your weapon/s, if you use same weapon, the drop rate will decrease.
- reloading the area also seem to help increase the drop rate
How long did it take to farm the scales? Just curious I've been putting it off for a while