I have multiple people in my neighborhood in Baltimore that sell stuff like this (detergents, soaps, deodorants, axe, febreeze, shower gels, razors, carpet, toothpaste and brushes, loofas, mouthwash). Including their food stamps. Well, not stamps but now they're debit cards that ironically say Independence on them.
So around the 1st-3rd of the month people get their stamps. They get enough in stamps that they can afford to sell some, maybe $200 FSD for $100 USD. Some folks actually budget and shop at the lower priced store like aldi, or food depot. So maybe a couple months out of the year they're able to sell sometimes more than half of the stamps that month. After that cash runs out for whatever reasons, a small minority, sometimes in groups steal from the local chain stores so they have quick cash. They're mostly drug addicts doing it for a fix or two for the day not for a living. But it's a daily thing.
One guy comes around often, sometimes everyday. He's got regulars sometimes he catches them on off-days and he'll need to come back to secure the sale. But fair is fair and he holds stuff for people. Most of his customers are the little old ladies you would imagine that spend hours peering over newspapers for coupons, or comparing the sales at store A vs store B. An $800 social security check doesn't go very far after expenses.
Seems like a way of life in the ghetto where I live. My family included, has always purchased these things from the guys in the neighborhood and still do. I'm not saying it's morally right. But as long as there is a cheap alternative to the corner store you will find someone in the hood willing to deal.