Here's a simple example.
A person is dirty and STINKS! The person smells HORRIBLE! People around gag. You mention how dirtyman stinks to high heaven and the person there says, "Prove it!"
What is there to prove??
Still, the "fact" is that someone is filthy dirty and stinks, yet you have someone disputing it....just because. (They prove just to be a waste of time)
A great example of how facts CAN be limited to what is observable AND how that observation is to be interpreted.
Anyone around that person well not deny that fact that he stinks, to them.
That someone may find that stench "ok" is another matter of course.
That the person in question is so comfortable with the stench that he/she can't smell it is also a fact.
None of that changes the FACT of that persons stench to all those involved the only difference is how that stench is interpreted.
Again, this is not the case with irrefutable facts.