Evaporated milk does eventually go bad after around 2 years past it's expiration date.
However even after the 2 years past it's expiration date the evaporated milk is still safe to drink as long as the milk has remained sealed in the can.
The canning of the evaporated milk makes the milk last for a long time but after a year or so the evaporated milk loses it's quality and won't be as fresh.
Still you can use the evaporated milk for many years past it's expiration date.
I buy evaporated milk cheaply at a overstock store and it's usually around 6 months past it's expiration date but it's still very good to use and drink.
Once you open the can of evaporated milk it will last for a few days before it starts to go bad so make sure to use it up before then.