Projection

It's very common for people to project their own unwanted feelings and judgments onto others. And it typically causes great suffering. The Dalai Lama speaks to this in his book, An Open Heart:

As we contemplate the way in which we project our judgments – whether positive or negative – upon people as well as objects and situations, we can begin to appreciate that more reasoned emotions and thoughts are more grounded in reality. This is because a more rational thought process is less likely to be influenced by projections. Such a mental state more closely reflects the way things actually are – the reality of the situation. I therefore believe that cultivating a correct understanding of the way things are is critical to our quest for happiness.

If we see things the way they are rather than make up stuff about them, we will avoid the kind of projections that cause suffering - both to ourselves and others.