A couple of days ago, I used some expired panko bread crumbs (expired by at least 5 months) for chicken tenders. They had this bad stale oil smell to them and I decided to take a risk. They had previously been opened but I'm very careful in closing them back up and storing them in a cool dry place.
As the first step of the recipe, I lightly fry the panko bread crumbs in a little oil and that removed that bad oil smell instantly. The chicken tenders smelt and tasted fine as well.
I read this and it says that bread crumbs don't spoil, the thing is though that it definitely smelt pretty bad. So, is the stale oil smell or the expiry something to worry about?
I use panko bread crumbs, but not that often, so they end up sitting around on the shelf for long periods of time. I've never noticed any kind of smell or staleness about them.
You don't say if the package had been previously opened or not. If it was, it's possible that the breadcrumbs were exposed to something in your kitchen which then sat in the package for a long time and ended up giving the bad smell to them.
That "stale oil" smell was probably the small amount of fats in the crumbs going rancid and forming butyric acid. I usually do not cook with anything that smells bad, my thought is that it just isn't worth the risk, but risk tolerance varies.
I check for smell also, but I think sometimes that smell is from the packaging rather than the product, but I still am hesitant to use anything that smells off.