your energy does effect your readings to an extent. But shouldn't effect them completely. Readings are based on energy, some of that energy can transfer into a reading, so reading your fears vs reality is very possible. That doesn't mean you need to be all Pollyanna energy for your readings. it just means your energy should be grounded and not erratic. Meaning you can be sad when you get a reading as long as you don't have that erratic emotions. Being happy isn't going to give you a happier reading or outcome. It just may help the energy be more stable and easier to read. Also, if asking about another person , if they aren't in a good state of mind then your reading on them won't be very reliable either. Meaning the energy they feel is what is being picked up in the moment.
Remember not all readers are the same, they all have different abilities and use them differently. A reader that is also an empath is the most likely to get affected by peoples energy. That can be good and bad. The importance is that your energy is stable, even if youre sad or happy.