The last 3 people that have told me they can’t ever get good Adwords Quality Scores were all direct linking to the affiliate offers they were promoting. They all said their quality score was fine for a couple days (good ctr and stuff) then boom… I suggested they use a jump page and when they did they were able maintain their good quality score.
Here is the thing… do you guys know that most affiliate companies auto geotarget for you? Do you also know that most of the humans at Google that check Adwords ads are not in the USA? In fact most are in India (from what people inside Adwords have told me).
So use your own jump pages when possible and when not possible do your own geotargeting to show non us users a jump page but us users the jump page.