In my opinion to gain money with ad-sense you need to blog about a topic the pay. I'm blogging about trekking and hiking, very poor! :-(
You need also to have a lot of traffic, but you need also that the visitor don't found all he needs on your blog, otherwise: why to click on another link?
If someone reach your blog with the query "How to crack word password" and with your post he learns how to crack a password, he reach his goal, if on your post there's nothing that really explain how to crack word password, probably he will click on an advertise about " How to crack word password".
I'm sorry for my bad English.