Newbie here, so this might be a dumb question - I'm trying to find keywords and keyphrases at low CPC. I've come across a few that show no local or global searches at all. As I understand it, this means that no one ever searches using those keywords or keyphrases. So if I start an adsense campaign using those keywords or keyphrases, no one will ever find my adsense ad? Is there a threshold amount of search traffic that you want for an adsense campaign?