I don't think it is so much a matter of where it is made so much as it is a factor of being a crappy clamp. Some of the cheaper stainless does contain iron. It's still considered stainless...but obviously, don't buy it. Also, stainless can go active (start decaying) if it does not have access to oxygen. I know that sounds counterintuitive, but it is true. It's best not to coat critical stainless steel things like hose clamps with anything. It's why "dripless"..hah! shaft seals have a water feed from the engines raw water system...also to eliminate any sort of air entrapment (bubble) as well.
Always use the type of clamps with the unperforated bands for anything that is below the waterline. Like these clamps:
West Marine: Heavy-Duty Type 316 Stainless-Steel Hose Clamps Product Display These clamps in particular are a metric size, so buy the metric size nut driver which makes tightening them down much easier than trying to hold a slot screwdriver exactly in place...usually while in some awkward position, around a blind corner, with only one hand available ...right? We have all been there.
The clamps that are perforated are not nearly as strong and they strip much easier in my experience. Like these:
West Marine: Hose Clamp Kit - 1/4" - 5/16" Stainless Steel Product Display