What is a healthy distribution of Cost and Revenue by Quality Score?
If you have anything under a QS of 4, with the possible exception of a brand new Ad group, you should probably just delete it from your account. There are factors tied to the overall quality of your whole account, so you don't want to get a bad reputation with Google for having a bunch of crap keywords. From there, your QS is going to affect your bids, as lower will cost more for the same audience. However, as long as your bidding for a ROAS goal, you can make money with a 7 as well as a 10. You should definitely aim to have as many high QS keywords as possible (through both keyword grooming and landing page optimization), but as long as you build from the high-converting core out to the mid-tail, and keep an eye on your ROAS, you should be fine.
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