This article aims to investigate the structures of 935 conferences organised by OMICS and 296 conferences organised by WASET from 2015 through 2017. These conferences are characterised in existing literature as so-called predatory or questionable conferences that provide low-quality academic meetings. We analyse 40,224 presenters, focusing on top-ranked institutions according to three global university ranking systems (Academic Ranking of World Universities, Times Higher Education World University Rankings, and QS World University Rankings). Our analysis shows that participants in OMICS events were primarily researchers from the United States, India, the United Kingdom, and China. WASET attracted more researchers from Turkey, India, and South Korea. We found that 11.0% of OMICS and 5.7% of WASET presenters were affiliated with institutions ranked in the top 100 in one of the three aforementioned rankings. We also found that both companies mostly organised conferences in cities that were top tourist destinations.