Yes, hydrochloric acid can remove some stains from stainless steel but don't use it. There are "friendly" as well as "unfriendly" acids with respect to the long term viability of the strength of stainless and hydrochloric acid is definitely unfriendly. Chlorides allow intrusion past the protective oxide layer on the surface of stainless which can ultimately lead to crevice corrosion and failure with essentially NO visible outer damage.
See the following site for cleaning stainless steel and read the last paragraph for the warning:
www.alvaradomfg.com/pdf/misc/stainless-steel_tips.pdf