in reply to
I haven't read the whole thread, so my applogies if someone has already mentioned this...
Take a deep breath when you walk into a new sushi place. Does it smell like fish? If not, you should be safe to proceed. Fresh fish has very little in the way of a "fishy" aroma. It's only after it's been laying around for a bit that it starts to achieve a smell of offensive proportions and a decidedly unpleasant flavor. At that point you have to start worrying about salmonella and such, so, correspondingly, the greater the smell the greater the health hazard.