Ok, defining Net Working Capital as the difference between current liabilities and current assets we get the situation that in fact, factoring does improve working capital. Through the selling of acc's rec'd this in turn ensures that working capital isnt tied up while waiting for credit customers to pay.
A textbook response, my response would be that it does both. While improving cash flow, working capital is also improved. While it could be stated that cash itself is a short-term asset, the reason for factoring ones accounts recieveables would be to repay debts, meaning money would be used for expenses relatively quickly (short-term debts), reflecting on the working capital.