Abstract We use a scanning tunneling microscope to investigate defects in the Ge(111)c(2 × 8) reconstruction. Topographic images of the same areas obtained in the constant current mode for two different bias values provide structural and electronic information, e.g. about local charge transfer in the surface. We study defects localized around rest-atom sites using this method of dual-polarity imaging. Possible mechanisms explaining the observed blocking of charge transfer from adatoms to rest atoms are discussed. Anomalies in charge transfer are seen along line defects. Finally, we find new, localized, minority reconstructions like Ge(111)-(8 × 8).