Running AdWords without conversion tracking is like flushing your money down the toilet.
That's a quote from Google AdWords Conversion Tracking 101/201/301 on Search Engine Journal, an in-depth article which ought to be of interest to you if you're running a serious Google AdWords campaign. Those of us who routinely manage AdWords campaigns wouldn't dream of not tracking response all the way through to some sort of conversion, but it's obvious that many businesses don't bother. And although it might come as a surprise, I can understand why they don't.
The thing is, most people in industry who book advertising aren't used to having the sort of feedback which AdWords gives you. When conventional adverts get placed in magazines, it's almost impossible to track the response (if you thought the bingo-card responses were the only ones the advert got, you'd never advertise). But AdWords offers itself up naked for inspection, and we're just not used to that. If you want to track the response in terms of website traffic, document downloads, name-and-address enquiries, even online sales, the facility is there with AdWords, and completely free. If you don't use that facility, sure, it can be argued that you're "flushing your money down the toilet". But it can also be argued that you've always advertised that way, just using a small amount of data and a large amount of gut feeling, so why not do AdWords in the same way?
It's a waste though.