The overture keyword tracker is heavily influenced by webmasters searching to check keyword bids and how high they rank. The higher the perceived monetary value of a keyword, the higher the inacurracy of the tool. It gives a good idea of what keywords to target but is basically useless otherwise. We dont need the tool to guess that poker is popular, but it really wont give us any useful information beyond that.
I have some top 3 rankings for keywords that apparently get over 1000 searches a day, yet I fail to receive 10 clicks a day.