Not really.
304 stainless is pretty stainless with fresh water. Not so much with saltwater. 316 is stainless in saltwater at normal temps, but not high temps. 400 series is both more stainless and less stainless than 300 series depending on conditions. And then there are the exotic ones.
And if all we're verifying is stainless after immersion in water, aluminum counts.
"Self-guaranteeing promise" is just a confusing way of saying "immutable properties after measurement".