Structural, photometric, and positional properties of galaxies in our sample, with visually selected GC-rich targets identified. The full sample of dwarf galaxies is shown as violet dots. Grey filled circles represent galaxies brighter than I_E = 16; the symbol size indicates the galaxy effective radius (upper left panel). Visually identified GC-rich candidates are denoted by filled orange or empty orange circles (the latter for dwarfs near bright galaxies). The grey shaded area in the upper right panel represents the expected locus for UDGs, as defined by van Dokkum et al. (2015) and in Sect. 6.