Men's rag & bone slim straight 15x jeans in size 38

Good condition men's rag and bone jeans Size 38 Button fly There is staining below the button fly of the jeans. I am not sure what it is. See photos. Can likely be washed out. Haven't tried to launder well. Hem was taped up and some stickiness from tape remains. The hemline could be ironed out. The tape has since been removed and the stickiness I'd imagine could come off with a good wash. These jeans were never altered, just taped where the hemline on the bottom pant legs are