Impurity ions with sufficiently high mass in toroidally-rotating tokamak plasmas are deeply trapped by a centrifugal potential well in the outer plasma midplane, with a bounce period that is shorter than both the bounce period of magnetically-trapped ions and the collision time. As a result trace impurity ions can undergo collisional transport at a rate exceeding that in non-rotating plasmas. Due to modifications to the effective magnetic field arising from the Coriolis force, the increase in transport is greatest for relatively low charge states of massive impurity ions in plasmas rotating in the same direction as the plasma current. These effects are quantified analytically and using test-particle simulations of tungsten (W) transport in transonically-rotating spherical tokamak plasmas. It is shown that the collisional confinement time of W ions in such plasmas can be two orders of magnitude shorter than the confinement time in the absence of rotation.