Why are we selective about the analysis or purports of the scriptures?

From: Mukund

Why are we selective about the analysis or purports of the scriptures? For e.g. we say that the number of wives (10 millions) of Chitraketu should not be taken literally? But then someone may argue that even “Krishna’s pastimes also should not be taken literally, they are just poetic imaginations”. Can you please explain how to decide which things from the scriptures should be taken literally or non-literally?