The training programme conducted by Durbar Mahila Samanaya Committee, an NGO working for the sex workers, is the same as that given to visually challenged persons who learn to distinguish between genuine and counterfeit notes through touch and from hearing the faint rustle of the paper.
In the last few months there have been several instances of customers slipping counterfeit notes to sex workers taking advantage of dim lighting at brothels in the Sonagachi red-light area, an NGO member said.
"There have been several instances where customers passed on counterfeit notes to sex workers, some of whom are unaware of them," said Bharati, a member of the Durbar Mahila Samanaya Committee.
"It came to light only when they went to the bank to deposit their money," she said.
According to a sex worker, it is the first time customers who are the ones passing on counterfeit notes the most.
"In most of the cases I received counterfeit notes from first time customers. I did not notice because they took advantage of the dim lighting in the cubicles at Sonagachi," she said.