In my Google Adwords campaign, I selected all countries, including Iraq and some E. European countries that I never heard of. Should I delete them to improve my CTR since they probably have some impressions, or I should just keep them so I might still get maybe one or two customers sometimes in the future?
My advice would be:
Don't advertise where there may be language issues.
Rate of exchange issues.
Prohibitions on the items you are selling in the country you are trying to sell in.
I would save the money and re-direct it into campaigns in markets that you know you can sell into.