What happened to this stainless steel tool when exposed to vinegar?
What grade of stainless steel was the clipper made of? Was it labeled stainless steel, or is this an assumption because it looked shiny or similar to some other corrosion-resistant object (which may itself be stainless steel or not)?
Test with a magnet: if they are non-magnetic, the clippers could be stainless steel. Without knowing more about the source of the clippers, I could guarantee you that they are not stainless steel - after, they were not stain-less even in vinegar.
It is difficult to imagine any kind of heat treatment or surface treatment (short of plating with a more active metal) that could result in this kind of generalized corrosion.