Unrealistic Expectations from Paid Search

It is one thing that Paid Search is measurable, and another that we want to measure it in a completely incorrect manner.

Paid search (and digital marketing) is not a panacea for all of one's shortcomings
It should replace the focus on making good products/ offering good services
It does not replace good prospect management
It does not replace, in many cases, human communication (face to face, phone, personal emails, etc)
In short it does not replace anything you would do with a prospect you meet at a trade show.

Paid search is only the beginning of a relationship. Post that it can still take the same time to close a sale, as when the lead has been acquired through another channel. Of course, it is important that one benchmarks the cost of lead acquisition through different channels correctly.