This work details a computational investigation into the impact of adatom defects on the adsorption of polyaromatic hydrocarbons on coinage metal substrates. While on a pristine (111) metallic substrate, coronene establishes dispersive interactions over an extended area and thus binds more strongly than similar-footprint hexahelicenes. However, adatom defects in the surface reverse this trend. The out-of-plane coiling of helicenes and their increased molecular flexibility enabled better adaptability to the adatoms' presence. Helicenes were thus able to achieve more energetically favourable conformations than the planar coronene adsorbate by coiling around the adatoms and tilting so that part of the molecular backbone overlapped with the basal surface. The loss of contact area on adatom substrates is partly compensated by the higher reactivity of the lower-coordinated adatoms relative to the nine-coordinated atoms within the pristine surface.