>>21476722 (OP)There are expiration dates (milk), and there are best by dates.
Expiration for milk is pretty spot on, it sours/curdles pretty much on the mark, maybe a day prior or after. You can make it last a wee bit longer with sealed no-air containment.
For best by dates, sometimes I ignore these, but I store my canned goods in a pantry in dark/cool temps. So shit won't go bad fast. I have yet to open anything and see/smell rotten stuff inside.
But I have tossed stuff that was 2-3 years past the date because I forgot about it. And that's just because I never used it, so I'm tossing it because I will never use it later, and it's wasting space.
As for opened stuff - I watch for mold and weird goop formation: if it looks wrong, it gets tossed.
I have yet to be harmed by stuff made at home - it's always fast food and restaurant stuff making me sick if something bad gets in me.