I once worked with a small company where essentially 100% of their PPC spend was wasted. Not half wasted, not mostly wasted, but completely wasted.

The marketing manager was determined to spend her budget though, for fear of losing it, so month after month she tinkered with keywords, rewrote ad copy, and the ads ran and ran, sometimes people clicked, views were tracked, but there were no conversions.

You're thinking maybe the conversion tracking was broken? It wasn't.

A handful of people searched for the company's name, and they did convert. The company ranked #1 across all search engines for its own name, so why they were running PPC ads on their name was somewhat of a mystery. At least it proved the PPC tracking was working... and proved the PPC campaigns were an utter failure :/

Watching $thousands being tossed away like that was quite sad. In one fractious meeting I suggested that it might be more effective to stop the ads, and stand on a busy street corner handing out the cash and asking passers-by to buy the product. It couldn't have been any less effective...