What's the overall effect of having keywords that match the minimum bid with no impressions and no clicks in a campaign both in the short term and long term? Any negative effects?
shouldn't as long as you aren't getting any impressions if you are getting impressoins and no clicks then that might be a problem
There is no overall effect as long as your keyword isn't inactive. Inactive keywords could lower your adgroup quality score. That is what I read from google.