I have inactive keywords in just about every ad group.. My question is: other than the keywords not showing up in search, are they hurting my campaign?
I have not found that inactive keywords have hurt my campaigns. Quantity doesn't matter, however if you have a large ratio of them, you set up your campaign or landing page poorly.
If some keywords are inactive then increase quality of landing page with that keyword so it will become active again. If more than 25% keywords are inactive then your ROI will come down.