Do these sites usually get any clicks? I just started a blog about the Buffalo Sabres (only spent like an hour on it, I have some more stuff to do to it, and once they play some more games I'll get a lot more content on there), mainly just for fun, but also kind of to hopefully get some clicks. http://sabresfanatic.blogspot.com
it does't matter; important thing is unique content and visitors! if your placement is good you will get good clicks then; i am also using adsense on sports blog and thats paying me!
You can use the Digitalpoint Adsense Sandbox tool to determine what ads would be displayed for specific keywords. If the ads are relevant to the content, you have more chance of getting a better CTR.