I find that a to better understand and assess different aspects of a paid search campaign, it’s important to look beyond the conversion and consider on-site behaviour metrics such as pages/visit, time on site, bounce rate, tendency to return. I recently wrote a piece on using Analytics metrics, instead of just conversion data, to help optimise AdWords campaigns.

There’s a huge amount of data out there that can help AdWords optimisation, and rather than relying solely on conversion data which, as you point out, can be unreliable, in my opinion its better to optimise based on user behaviour and engagement, and leave one-click and multi-click conversion data mainly for reporting purposes.