Is brown sweetened condensed milk good or bad?

Sweetened condensed milk can be brown for two different reasons:

1. It is old and has reacted with the can - don't use it if this has happened. Check the date on the can, and before using any can check the seal was unbroken.
2. It is caramelised condensed milk. This means the sugars in in have been converted into caramels and are darker in colour. This can be done before or after it is canned. This golden brown sweetened condensed milk is fine to eat. Either the label will tell you that this is caramelised sweetened condensed milk, or the place or person you got it can tell you whether they have caramelised it.