Although these potions are rare, dip-testing to these will result the loss of polypiling objects conduct. Because of this, some conduct players try to price-id the potions and identify the 200 zm potions otherwise. Besides formal identification, one such way is monster inventory. Only three types of price-200 potions can be generated on random monsters: full healing, speed, and polymorph. Polymorph is by far the least common one. Death drops and items picked up by monsters complicate the picture, but a throne farming pacifist will reliably isolate all three. The other two can be eliminated by alchemy output and monster usage.
Note that you can also cause a monster to polymorph by wielding the potion and smashing it on them, but this is not advised because if by an unlucky chance that monster becomes a cockatrice, you will be petrified.
Monsters can quaff this potions. Mercifully, this will not generate out-of-depth monsters.