I had the opportunity once to speak with a project manager at a large company whose development team had fashioned a fairly rigorous automated development testing regimen. They had a high degree of tests at all levels and had built a fairly robust auto deployment process via their build. From time to time, however, the team would deploy their application into company wide production with glaring UI specific issues, such as pages with broken tables and missing images. It was particularly painful for this manager as he would inevitably find out about the issues from various groups within the company who depended on this application. It turned out that this team was so heavily focused on automation that they neglected to utilize common sense and had never actually manually checked the state of a deployment. Once a manual sanity check was put into practice, UI ugliness issues largely disappeared.

Best practice: be sure to run a manual sanity check after a deployment before your users accuse you of insanity.