I feel this is a stupid question, but I don't have any experience, so here goes.

Carrying swags on roof racks. Don't they get all wet and dusty & dirty and when you roll them out to use they will be unuseable because of it?

Or do they somehow magically stay pretty dry & clean?

Now I don't have a ute any longer, the swags will have to go on the roof of my wagon, hence me asking.