Instrument your code with explanations so it's not a mysterious black box, but one that explains what it does.

Use the static Explain class to instrument your code:

var properties
    = from p in candidateType.GetProperties()
      where HasDescription(p);
Explain.Step("Found {0} candidate properties", properties.Count());

if (property.PropertyType() != typeof(bool))
{
    Explain.Decision("Property {0} is not of type bool", property.Name);
    return null;
}

To collect all the individual messages together into a single explanation, wrap use of the instrumented code in an ambient Explanation:

using (var e = new Explanation())
{
    // Anything explained here will be collected in the explanation
}

The messages can be accessed anywhere by inspecting the Details property or collected at a point in time by creating an instance of Explainable<T>.