I'd been reading that using an ASIN as a keyword was better than using the title of the book because it would be more precise. So, I conducted a small experiment. I looked at the top impression getter for a book title in one of my ads and added the ASIN as a keyword for that book. The results are astounding. The book title still gets thousands of impressions without fail. The ASIN? Zilch. Zero. Nada. Not one single impression after two weeks. Is there supposed to be some sort of secret on how to use the number? I know we can't be expecting people to be searching for books by ASINs. I don't believe I've ever searched for a book that way and doubt anyone else does, too.
So, what would be the point of sticking an ASIN into a keyword slot in an ad if it's not going to bring up even one impression?