The following linked article from The Register accuses Google’s AdWords, namely the ‘automatic matching’ feature to be untargeted and an outright waste of funds in most instances.

In short, automatic matching weakens the parameters and rules of defining ‘targeted’ in PPC terms. If I sell Adidas shoes, the articles explains, I don’t want to come up for a search on slippers. That would simply be a waste of money. I would go as far to add that in today’s world of short attention spans, anything not directly or literally an Adidas shoe is not targeted enough- let alone slippers.

Pay per click is too reliant on the ‘conversions to dollars spent’ ratio to allow for any more leniency than exactly what I typed in. Again, attentions spans generally don’t allow for it. Additionally, if the search term in question is on the general side where this rule may not directly apply, then the traffic itself will be of the browsing type not the converting (purchasing, buying, targeted lead) type. So in this case my clients probably aren’t interested in the 1st place.

But that is a whole different argument in itself.

http://www.theregister.co.uk/2008/03/18/when_google_does_evil/page2.html