Many things can affect stainless, even simple salt water if you don't take care of it.
Here's some good info below:
Stainless bucket:
Stainless steel is common chromium/nickel alloy steel used in thousands of products. A protective chromium oxide film forms on its surface which gives stainless its superior corrosion resistance property. When properly maintained, stainless provides excellent luster, strength and durability. If the scoop has been electro-polished....this is a process which involves a chemical bath, electrical current, and temperature control. The benefits are a pristine finish, extra hardness and corrosion resistance.
Some scoops on the market are just painted silver in the weld area. In most applications, stainless will not rust or stain even after many years of use. However, stainless steel is not stain or rust proof. When used in contact with chloride salts, sulfides or other rusting metals, stainless will discolor, rust, or even corrode. Proper care and maintenance of stainless in marine environments where stainless may be exposed to corrosive elements will help keep the stainless product beautiful and functional for years to come,
Always –
Clean stainless frequently with soap and water especially after use in salt water. If any rust spots occur, remove only that area with a stainless cleaner. You can keep the shine on the product by using a car wax.
Never - !!!
Use coarse abrasives like sand paper or steel wool on stainless.
These may actually cause rusting.
Never- !!!
Clean with mineral acids or bleaches.
Never - !!!
Leave stainless in contact with iron, steel or other metals which cause contamination that can cause rust or corrosion.