While the quality of the generated molecules indicate a high relevance of the proposed scoring function for de novo drug design, we furthermore qualitatively evaluated its usefulness to filter out undesirable compounds. This was studied especially in the light of existing rule-based approaches, such as the NIBR filters, which are routinely used to deprioritize and flag problematic compounds before consideration. Ideally, our goal was to rationalize compound features not necessarily captured by such methods currently, but that are at the same time considered as undesirable by medicinal chemists. Towards this goal, we manually reviewed molecules from the initial pool, which had been already filtered with simple properties as well as with the aforementioned rules, and then visually inspected ones that were assigned a high score by the proposed function. Figure shows four of such compounds. While there are some features that could be described as unattractive and can be captured with a generic SMARTS pattern (e.g., the terminal alkene in compound b, or the aromatic nitro group in compound c), the overall "unattractiveness" seems to be driven by more general properties. Based on our subjective opinion, among others these seem to include compound complexity (c and par-