I'm not overly strict on "use by" dates with a few exceptions. Diet soda goes south fast after it goes out of date. Canned tomatoes. I was making chili a few years ago for a charity event and thought I had enough diced tomatoes to do a big batch. I didn't. We have this country store out here in the sticks, so I went there for some, never paying any mind to the dates, it's a store, after all. Well, I get back to the house and start opening cans, and the contents were nasty, and kinda purple in color. Turns out they were a couple years out of date.
I did take the nasty cans back, and found enough cans that weren't expired to finish the chili in time for the event. When I nook that nasty stuff back, the guy who owned the store at the time told me he didn't know how that happened since he and his wife took the older stock home and replaced it with new. Next time I was in the store, I started casually looking at dates on the canned goods, and was hard pressed to find any that weren't past the use by date.