I am using many keywords (about 100) and 10 adds. I know, I should make a better targeted campaign, this is the next step.

This is my question though:

For a certain keyword, the Quality Score is very low. BUT, I am using 10 different adds. One of them, in my opinion, is a very good match for the keyword.

So, the Quality Score corresponds to WHICH one of my adds? All of them? The Best/worst match?

I know that I should better design my campaign strategy. But still, I expected Google to pick the best add for the correct keyword.