Many amateur astrologers look at a birth chart, see a planet in a specific house, and immediately jump to a textbook conclusion. They think, "Mars in the 4th means Manglik, so the marriage is ruined."
Dr. Rishi Rohit Sharma uses a brilliant metaphor to destroy this simplistic thinking: Salt and sugar look exactly the same (white crystals), but if you put salt in your tea, it is ruined.
In astrology, two charts might look identical at first glance. But a slight aspect ("drishti") from a friendly planet, a hidden conjunction ("yog"), or the inherent nature of the ascendant completely changes the "taseer" (effect) of the planet. What looks like a curse might actually be a hidden blessing.