I had a campaign I started the morning of the 24th. It went good, I hit the amount I wanted to spend for my testing. Pulled it out of my testing account, put it in my permanent account the morning of the 25th, and when I inserted it, it is showing a QS of 2 now instead of 8! It has the same exact everything; keywords, ad text, website, etc. What happened?
If the two accounts are tied to you with your same billing in each - Google might think that you are trying to compete against yourself to dominate the front page. They might have seen this and given the new ad a bad QS because it doesn't want you to have 2 ads in the same category in two different accounts. Just a thought.
Sometimes also you can have a high quality score initially, and then it will get manually reviewed and slapped.
Adwords uses the accounts history in determing QS... a poor account rating won't gain higher score when campaigns are added.