Is it worthless? It has $8 CPC but nothing is coming up in the contextual targeting tool. Would I even be able to make money from this keyword from adsense if I ranked it?
That is a matter of what keyword tools say about traffic and spy tools say about the number of competitor ads there are within that keyword results page.
Do a little more research and don't put all of your faith in one software's results. Be sure and check with multiple options, so that you can do a calculated comparision first.