The "not cleaning" comment was intended to be neither useless nor insulting. Sorry. It was just emphatic.
Vinyl that has become stained and begun to bleed plasticizers to the surface is notoriously difficult to clean and it doesn't stay that way. The OP stated he only used the cord twice a year, so cleaning it, only have it become dirty again within 1-2 uses, is cruel. I think he did not understand just how quickly vinyl does that. This is also why so many suggested covers rather than cleaning. I'm not alone.
It is just the nature of vinyl fenders and cords. I hate to see sailor waste elbow grease because of a mistaken belief that clean is always important or even achievable. Clean deck, linens, and carpets, yes. Clean fenders and cords, not so much.