>then sell the gift cards for "clean" money at a discount from face value.
This seems to be a misconception about how money laundering works. The "cleaness" of money isn't an attribute of the bill (unless you robbed a bank and they recorded the serial numbers), it's whether you can plausibly say it originated from a legitimate source. Taking dirty money, buying starbucks gift cards with them, and reselling them doesn't help you prove you got the money legitimately.
If you sell them, you still end up with cash, and any transaction records isn't going to help you. "Oh, you got this money from selling starbucks cards? Can you explain where you got $10000 worth of pre-activated starbucks cards?"
The model of a laundromat is a cash based business with high margins. You'd "buy" $10000 worth of widgets from yourself, buy $1000 worth of "materials", dump/trash those materials (so they don't pile up), then claim $9000 of profit as "clean" money.
