I've been running a campaign for the last 3 weeks with about 5,000 keywords and of course only a handful of them are driving traffic. Most of the other keywords have zero impressions/clicks. So I wanted to know if having these no-impression keywords in the same campaign and/or adgroup as the other nicely performing keywords negatively affects the overall quality of your campaign/adgroup?
Having keywords with no impressions does NOT affect your group or campaign. Quality score is calculated by ad-keyword combination. A keyword with no impressions just sits there gathering no data so it can't affect anything else.