Go with your gut. If it doesn't smell right, that's your body's way of sayin' "don't eat it," in my opinion.
I'm a fan of "the sniff test" too. lol. I've tossed many things out that I'd already cooked just because the smell didn't sit right with me. (Although, the sniff test doesn't work for things like sour cream--which, if gone bad is still undetectable unless there's physically mold on top of it.)
Salmon should not stink. Yes, there will be some seafood smell to it, but it should not be a pungent odour that makes you wanna gag.

