Household Bundles on Buy Sell Trade groups?

Does anyone else know what these "household bundles" are about in local Buy, Sell, Trade Groups? They always seem to be just a random assortment of detergent, soap, razors, and some of the sellers seem to be weirdly aggressive. Is this a euphemism for something else? Are these people using their government benefits to buy approved items and then getting cash from people? Or is there just some weird micro-economy of toilet paper and toothpaste that I'm just unaware of?