Foundation Problems: Is there really a problem?

I recently posted a question on Trulia to this effect:

Foundation Findings? What is acceptable variation in the foundation?
I hear 2-3 is the norm and that no foundation is ever zeroed out? One engineer tells us that it slopes and to have it repaired. The other says there are slight variations but does not suggest any repairs? The slope claiming engineer used a water level. The variation claiming engineer states that a more expensive tool called a zip line level should be used for more accurate measurements? No cracks or sticking windows present. What would you advise to your client?

I received many responses that can be read here:

After a few long days of sleepless nights and a crash course in foundation repairs I have been able to come up with this acceptable conclusion for folks looking for an answer to my question.

The owner of the foundation company explained to me that there is a measurable amount of moisture that is trapped underneath the slab when any foundation is poured. Over time the trapped moisture dries, which causes the soil to compact and crack, which causes the foundation to shift.

Foundations leveling standards are determined on a case by case basis. In this case the home was evaluated and thereby concluded that a level cosmetic appearance and structural integrity would be the determining factors when performing the contracted workmanship. The owner further stated that if any foundation is corrected to its originally intended level surface that the foundation would raise but would create voids in various parts of the house, thereby causing sagging in the foundation and could create potential for further foundation failure.