Yeah. I have a small pocket knife i carry everywhere, it is stainless. I've had it for years, and frequently bring it in the water with me clipped to my swim suit (incase i need to cut a tangled rope). I wash it like a dish with soap and water, i use it hard and put it away wet, and it has been fine for years and years.

After all this, i took it on a single trip in salt water, it spotted with rust that night.

I also have a Sig P938 SAS which has a stainless slide. I keep that dry and oil it on occasion, and yet that one spotted with rust within a year despite me taking good care of it. Luckily sig replaced the slide but this taught me one good lesson.

Different grades of stainless make it different grades of rust resistant. Kind of like calling IP67 electronics, like the iPhone 7, "waterproof" when they can only really withstand splashing. Some can get dunked, some can't.

Absolutely. Why would they call it less if it's actually never? That would be exceptionally terrible marketing.