The cards are just paper and ink. If the reader is tapping into the universal consciousness, how could their reading be construed as negative, or personally biased?
Because even if you believe that a reader is tapping into the universal consciousness, she does so by means of her personal consciousness. She pulls the cards, which may present universal symbols, but she must then interpret those symbols using the tools available to her as an individual, and it's altogether possible for her personal beliefs to influence that interpretation.
However, I think that's a matter of beliefs or prejudices affecting a reading, and
not some sort of fabled negative energy. I second Closrapexa's statement:
I just don't like to classify people as "negative;" that seems unfair and victim-blaming. Everyone has issues, and nobody is completely negative, nobody is all dark and foreboding and must be "protected against" as if their "negative energy" was the plague or something.
To say that a reader who is experiencing hardship--especially if it's a form of mental illness, which is
not the reader's fault--is inherently negative and is therefore a burden to others seems ridiculously cruel to me. As Tanga said, it would be unprofessional for a reader to allow events in her personal life to color her readings too much (e.g. Cheryl just got her heart broken and now every love reading she performs predicts disaster), but that's not a matter of "negative energy". It's a question of interpreting what you see in the cards fairly and truly. It would be just as problematic if it was unreasonably positive (Cheryl just started dating again and every love reading she does is full of promise). A reader's responsibility is to show what the cards say, and not what she
wants them to say.
But this is most certainly not something that can be ascribed to "negative energy". People experiencing severe depression--and people who are not struggling with mental illness, but who are experiencing stress in their lives--can still be excellent Tarot readers, because they read the cards as they fall.
Furthermore, AmethystEyes, I take serious issue with your contention that:
I do disagree on people not needing to be protected against negative energy of people. Emphaths especially need to do so, it is so draining and unhealthy to be around these people.
No one needs to be "protected" from people who suffer from depression or other issues that might make you perceive them as negative. You as an outsider cannot possibly understand the difficulty of the issues those people are dealing with (although, theoretically, an empath ought to be able to), and rather than dismissing their problems as "draining" on you, I would recommend exercising a bit of compassion and thinking about their health before your personal comfort.