Modern manufacturing and installation processes for glazed façade often produce visual defects, especially for large panels. These visual defects are often noticeable and observable, but very few methods exist to quantify and evaluate them on site. The complex facades become, the higher is the need for in-situ assessment procedures that can facilitate quality control. This paper reviews current knowledge of optical glass defects and related assessment methods to highlight current gaps in assessment methodologies. In particular, this paper highlights with examples and evidence from field study, the need for novel cost-effective and practical methods that can capture the subjective visual nuisance, which is often not sufficiently quantified by current existing methods. Characterising the perceived visual nuisance is often essential to ensure quality control but also gather evidence and data that can inform better design and manufacturing of facades. However, little has been done to provide reliable and consistent methodology that could allow practitioners in-situ assessments.  Therefore, this paper first reviews current assessment methods. Then, it presents new emerging methods that can sufficiently describe the level of visual nuisance perceived by an observer due to the defects.