How to Confuse an Undead Chicken

... or, an undead chicken book writer, at least. ANyway, here's how:

It sounds simple, but I'm confounded. The ads run, and they even work fairly well, but the keyword ratings are so far off that I'm just ... well ... perplexed

Example: go to a site specifically about a zombie chicken book. Look around that site, and see what kinds of keywords you're seeing. Words like "book" and "zombie" and "chicken" and "cluck" and "horror" and "novel" ... and hey, I'm not loading keywords or anything, it's just that I wrote a book about zombie chickens. And yet the following keywords are ranked as "poor" in Google adwords:

• book
  
• books
  
• horror
  
• chicken
  
• zombie
  
• horror book
  
• horror fiction
  
• ... you get the idea.
  

The real confusing part is that I used the keyword tool to extract valid keywords from the site... I just don't get it. I really don't.