I went for a walk at the beach this morning and thought of this thread when walking down the stairs. The railings are all stainless and I noted the railings that get touched were shiny but the lower parts of the railings that do not get touched were showing tea stain.
The shiny parts were clean and the tea stain parts were dirty so I would agree with an earlier comment that clean stainless will not corrode as the protective oxide layer can be formed.
Regards
Pete:U