Further,
The works that are not from faith, but from the context of earning, don't taste so good - being tainted with pride.
you will know them by their fruit - it's a taste test.
We can tell without actually tasting sometimes after knowing a bit about the tree - who tended to it, etc., but the best way is taste.
Trees can have no fruit, good fruit or bad fruit - and the taste test tells us about the tree. 'Good looking tree' does not necessarily mean 'good fruit', even if it's an indicator - and an odd looking tree can produce very nice (humble) fruit, rooted in good soil.
I'm sure that people who post here have tasted some sour fruit.
Bang