Every year when Durga Puja approaches, a certain Kumortuli in Kolkata is thrown into frenzy. Kumortuli is the land of artisans in North Kolkata. They supply the idols to most of the pujas. Making the idols of Goddess Durga, along with Goddesses Lakshmi and Saraswati and Lords Ganesha and Kartikeya is a daunting task in itself. For the entire puja to be auspicious, the idols need to be created with the right mixture of punya mati or blessed soil. Source: The Hindu

No one is sure how and when the custom of getting punya mati from this forbidden territory came to be. But as it goes, the priest must beg for the soil from a sex worker. It is as if irony had decided to pull a prank. And while the soil is being scooped and handed out, the priest must recite a particular mantra.

Source: ANI News

Along the years, many reasons have surfaced. Mostly, it is believed that when one visits these women, they leave their virtue and piousness at the doorstep to enter a world of sin. So, the soil at the doorstep is said to have imbibed all the virtue and piety of all those who visit.

This easy transformation from piousness to sinfulness is only highly questionable. But that is a discussion for some other day.

Source: TheOcult