The search query “ten commandments in the bible” shown 7.29% CTR in my Web site about Old Testament. I wondered and enjoyed this surprisingly high CTR.
I kept using this keywords based on high CTR, despite it is not quite relevant (it is too specific for a general Old Testament site).
But later Google told me that for such keywords bounce rate is very high and suggested me to add “ten” to negative keywords (what I did).
Conclusion: Select AdWords keywords based on common sense whether they are relevant, not on CTR.