Informal economies exist between the margins of state and non-state sanctioned economic activities and are often considered impenetrable to investigation and analysis due to their opaque and clandestine nature and their fluid and dynamic operations. In this updated chapter of a 2013 original scoping study of qualitative and quantitative measurements of shadow economy activities in the Philippines, new qualitative research methods are given prominence, and a brief review of their effectiveness is presented. This chapter showcases pioneering efforts to improve and develop new qualitative methodologies and determine other proxy indicators that can be used to analyze both the coping and pernicious informal economies that exist. Central to this chapter is the premise that informal economies are not immune to interrogation and examination, and that various sophisticated techniques are being discovered each year. Using the methodologies utilized in the Philippines study of shadow economies in Mindanao as a template, the chapter goes on to enumerate and elaborate evolving qualitative methodologies particular to the study of smuggling and related illicit economies in parts of Southeast Asia and Africa.