Stainless steel does not rust in itself, which I am aware. Rust on stainless steel may only occur if this was happened from outside. So stainless steel is still rust if you give on this one iron chip and a little water. Then even no longer widertseht of stainless steel that rust attack.
But what the hell has this to look at the inside of my pots? Outwardly, this impeccably made, so I can rule out impurities in the water again, because otherwise the pots would begin also to deneren points to rust. A pure polish is namely certainly not deter the outsides of the rust. So for me there is only the reason to believe that this steel is of inferior quality.
However, I assume that these pots a further and can tell the build quality to be anything negative. Were it not for the rust stains, this would be a great pot set at an unbeatable price.