I got in an argument with my room mate over what it exactly means when something is a hard truth, so I ask you as well hubski, what is a hard truth?
Something you REALLY don't want to hear. Something that goes against your beliefs but is 100% factual. Stuff that hits you as though you just heard you were just diagnosed with terminal cancer. It's true, and that's the end of it. It doesn't even necessarily undermine your worldview, it just leaves you shaking, like you're gasping for air. That's a hard truth.
The hard truth isn't necessarily given harshly but given with no regards to someones feelings about the subject. It is something that is told like it is rather than being vague and indirect. I usually associate it with someone who cares enough about your well being to tell you what you need to hear versus what you want to hear.