I would be more worried about silver/selenium/iodine stains than acid stains

You are using sulpho-chromic solution at work, that thing is nasty!!!! Excellent to dilute any sort of organic (carbon-atoms) in metals, glass, nalgene, teflon, etc.

acetic acid is not even close... but be aware of glacial acetic acid can cause pretty bad skin burns... once diluted is pretty much harmless.
And you can always use CITRIC acid