The ability to turn everything one touches to shit.
The phrase is a mash up of the King Midas myth of being cursed that everything he touched turned to gold and mierdas, which is the spanish word for shit.
There is some controversy as to whether the object touched was already a piece of shit with an exceedingly thin veneer of gold plating, where the Mierdas Touch serves only to reveal the subject’s true nature versus the Mierdas Touch actually turning any object into shit, even if it was previously unblemished.
The doctor was beloved by all until he was touched the Mierdas Touch, wherein, it came to light that the doctor was constantly drunk, mis-prescribed drugs, and belittled underlings.