Method for the optical inspection of containers, where the containers are transported with a conveyor as a container mass flow, where the containers are each captured with an optical inspection unit as first image data, and where the first image data is evaluated with an image processing unit for contamination and/or defects on the respective container, where the first image data of several containers is overlaid to form an overlay image, and where the overlay image is evaluated for the presence of points of contamination in a beam path of the optical inspection unit.