When Bologna has gone bad the surface of the bologna will usually have a pretty slimy surface or start to smell rotten.
The Bologna that has gone bad will have a bad smell to it and should be thrown out and not eaten because it can make you sick.
Bologna is kept refrigerated properly should last for 7 to 8 days.
You can keep Bologna Longer by placing it in the freezer and the Bologna will keep in the freezer for 6 months to a year although it won't be as fresh but it will still be good to eat.