A dishwasher seems like a good way to clean them, but they should still be autoclaved afterwards. Doctors are notoriously cheap though, so I can't see them "investing" in 2 machines to clean and sterilize their instruments. They either have a dishwasher or an autoclave, not both.
I've seen some really slipshod cleaning of instruments. Handwashing can leave a lot of gunk behind, but folks think that if an instrument is being autoclaved, the washing process doesn't matter very much. I've seen nurses just swish a batch of used speculums through a basin of plain water (same water for the whole batch) before bagging them up for autoclaving. It's really horrible to open a freshly autoclaved instrument and find blood still on it from it's previous use. It doesn't matter that it's sterile blood...it's still horrible.