The interaction between small molecules - such as drugs or molecular sensors - and nucleic acids remains a central topic in chemical and biochemical research, due to its relevance across a wide range of systems and applications. These small molecules typically feature aromatic moieties, which promote interactions with nucleobases via π–π stacking and intercalation. This binding is also associated with the known “light switch” effect, resulting from restriction of intramolecular motion (RIM). Simultaneously, aromatic compounds often undergo self-aggregation, driven by the same π–π interactions. Spectrophotometric and spectrofluorometric analyses of such systems must therefore address the competition between dye-dye and dye-nucleobase interactions. The observed emission enhancement - whether due to RIM or aggregation-induced emission (AIE) - often reflects a complex interplay of overlapping phenomena. This complexity can hinder accurate interpretation of experimental data and the reliable extraction of binding constants. In this contribution, we present selected case studies from our research [1]-[7], highlighting critical challenges in data analysis and the evaluation of experimental errors.