Which of the following is NOT a deficiency that could be shown in a visual inspection?

The option that indicates a perfectly adhered membrane is not a deficiency that could be shown in a visual inspection because it suggests a proper installation without any visible flaws. In contrast to other choices, a perfectly adhered membrane signifies that the air barrier system is functioning as intended, creating a continuous and effective air seal. This state is desirable and indicates that no gaps, delaminations, or other issues are present that would compromise the air barrier's performance.

The other options represent various deficiencies that would be visible during an inspection. Fish mouths indicate an issue with the material's application, where sections are not properly bonded, leading to potential air leaks. UV degradation results from prolonged exposure to ultraviolet light, which can damage the materials and is observable through visual cues such as fading or warping. Overlapping materials can create vulnerabilities where airflow may penetrate, making it a concern that a trained inspector would identify through visual assessment. Each of these issues undermines the integrity of an air barrier, whereas a properly adhered membrane does not reflect any shortcomings or concerns.