I agree that most things will be fine for varying lengths of time beyond their 'use by' dates, and generally it comes down to common sense (smell, appearance, etc) but once in a while you can get caught out.
About a year ago, I ate some hummous that I had already opened and eaten some of when it was still 'in date'. The second time, it was only one day over its sell by date. It looked fine and smelled fine, but I was violently ill.
After 3 days of vomiting and enduring excruciating stomach cramps, I called the NHS helpline (wasn't registered with a GP at the time)
I was told that hummous is particularly lethal, because it goes off quickly, and breeds both salmonella and listeria! I was told to expect to be ill for a week, and indeed I was!
Took me a long time to try hummous again!