Some stainless steel more stainless than others I'm rather disappointed in the latest stainless steel bowl I bought. Left it in the sink unwashed from a salad for a week while I had to be away, came back and it had rust underneath and inside. Same has happened to few other bowls, pots and utensils over the years, all marketed as stainless steel.

At this point, the only 3 stainless steel items I have that are truly stainless and have lasted me over 10 years are a water kettle, a spoon and a pot that my mother gave me when I first moved out.

Everything else has either rusted or developed these black pits which I have no idea what they are. My dough hook for example gathered more and more of them until it finally snapped at one of the pits locations. 

So how can I identify things that are really made of stainless steel? I want more things like my pot, its got scratches and discoloration from lots of abuse but is still shiny.
Yes, there are different blends to make 'stainless' steel and some are more resistant to rust (higher chromium and nickel content), or to pitting (higher molybdenum content) or hold an edge better (eg, 'surgical steel'), but to my knowledge, all of them are prone to pitting if they've exposed to salt water for a long enough period of time.

The exception to this is if the water is boiled before the salt is added, as it's a chemical reaction between the steel, salt, and dissolved oxygen.  This is why many recipes for cooking pasta tell you to wait until the water is boiling before you add salt.

Salt can also speed up the rusting of stainless steel, so it's a good idea to rinse things off if you're not going to clean them right away.  Salad dressings typically contain a fair bit of salt, but it's also quite possible that the bowl is a lower chromium steel.

update: Although there's now another system for grading stainless for the building trades, you'll often see stainless steel sold mentioning '18/10', which is a more rust resistant blend.