Clarifying Rahu and Ketu
Q: I understand that planets have both high and low dignities, so even the natural malefics like Saturn and Mars can cast dignified and positive qualities when well disposed. But, I always thought Rahu was always negative. Even when conjoined with benefics, it tends to expand the less dignified aspect of the conjoined planet. Also, the pastime associated with the appearance of Rahu and Ketu does indicate that they are originally demoniac…
Although there really is no siddhānta in astrology, there are a few books that are clearly better and more authoritative than others. Bṛhat Parāśara Hora Śāstra for example, and Phaladīpika. In my opinion, BPHS is outstanding for mathematical techniques to assess the fundamental facts of a horoscope very objectively. But the Phaladīpika is outstanding in its presentation of interpretational guidelines and examples.
Phaladīpika, in my opinion gives the most rational and useful definitions of several basic interpretational constants. The author states clearly and definitively that Rahu and Ketu are neither krura nor somya (aka neither malefic nor benefic). They are entirely unlike the seven true planets. They simply mimic whatever they are in contact with.
My experience as an astrologer does not match the idea you stated, that Rahu or Ketu will always spoil whatever it contacts. If this is true, Paul McCartney would not be Paul McCartney (Ketu conjoins his ascendant). What to speak of Paul McCartney, our Śrīla Prabhupāda has an extremely strong and tight conjunction of Jupiter with Ketu. So the idea that you have presented that Rahu and Ketu spoil everything is completely bogus. The truth is that Rahu and Ketu powerfully amplify anything they contact.
Consider the tale, they are dopplegangers (shape changers).