After looking up the ingredients in a no bake cheesecake box mix, you should be able to tell by smelling the mix. If it smells acrid like rancid oil or butter, throw it out.

I often find that there is a build up of dried milk around the container opening that smells sour. When I'm in doubt about the milk in the container, I pour some into a glass and then smell to see if it is still fresh. More often than not it's still ok but keep in mind that it would be a good idea to drink soon or keep it for baking.

I always smell and do a visual inspection of expired items before cooking or consuming. When in doubt, it gets tossed out. So far I've suffered no harm.

"Best Before" doesn't mean "Bad After" it just means that the company has decided that the product is at optimum quality at that date.

Watson

..... right on! ............. though it should be noted that a product may not last until it's Best Before Date, because of how we the consumer have handled and cared for it.

A prime example is milk ... how long was it out of refrigeration from when you purchased it in the store until you got home? Was it -22°C for that drive? or +38°C? Is it removed from the frig, glass poured and returned to the frig? Or does it sit on the table for an hour during a meal? Or longer, while family members come and go from the table? Is the container/bag closed/sealed between uses? Or opportunities for cross contamination with other foods? etc.

This is just an example using milk, but you can take the same concept and cross it over to other food items.

To tell if milk is spoiled, pour some into hot liquid, tea, coffee, or plain water. If bad it will curdle.

We go through about 4 gallons of milk a week, one daughter is a huge milk drinker. However, I have noticed that if the milk gets near the expiration date, usually it starts tasting strange a day before the expiration date.