Internal cleaning of inverted cans includes engaging a can's cylindrical wall with a wall-conforming vacuum or adhesive gripper, causing a spraying unit to travel axially in and out of the can's opening while the can is inverted on a circular conveyor, and using a supporting arm or bottom stop to subject the can to a counterforce against a flushing force from sprayed cleaning medium. This prevents the can from being pressed out of a receptacle in which it sits during cleaning.