It should come as no surprise that corners get cut in audits. I wouldn't call it cheating per se, nor am I defending those who blatantly gundeck (a Navy term for cheating on assigned tasks) for a few reasons, but here are two:
1. In smaller/medium sized companies, resources generally don't exist to carry out the full scope of even the most basic audit frameworks (measuring against 800-53, ISO, etc.), thereby leaving gaps in the completed audit when compared to the plan.
2. In larger companies, the audit teams report to the board of directors, not the ISO or CFO as will the Risk team or Information Security team. Auditors get treated like every other auditor.. they get what they ask for -nothing more, nothing less. I've worked as an auditor, and worked with auditors several times in the past eight years and know the drill quite well. If an auditor is uninformed, they don't ask good questions, and as a result, get inaccurate information.
Tips for doing better audits?
1. Look for experience IT/Security people that can be taught auditing. Certifications are good, but not perfect. CISA is common among the large consulting organizations, but again, personal experience leads me to believe that not all CISAs are created equal.
2. Create an environment of cooperation between the audit team and the infosec/risk team. If an audit is going to happen at a certain location, why not leverage the audit team to perform a risk assessment at the same time. There's an opportunity for resource sharing if you can get legal to sign off.
3. Cross train and labor share. Use infosec people as auditors, and get auditors involved in sitting in the SOC. This makes everyone smarter, and eventually, the company better.
4. Find a good framework and stick to it. Measure the results location versus location, program against program, or division against division. It's not a report card but a score card that offers baseline, and hopefully upward trending.
Most importantly, remember, auditors get treated like auditors. They're outsiders and need to know what to ask, and whom to speak with to get the right information. They get this through bonding and familiarity in the organization. Train them well, get cooperation with infosec, and you'll see markedly better, and more consistent audit results.