This is going to be all about noticing a hoard. It can come in many different forms. It does not always mean it is dirty or unkempt. Some hoards are very organized. They can be the most tedious removals to complete. My great-grandmother's home was very clean and in the companies view very organized. However, behind the bedroom door lay a well-organized Tetris of Avon boxes, paperwork, and a hoard of lifelong items that she had collected in the 40 years she had lived in the home. That wasn't the only room. She had a front room that was 15x10 packed full of purchases, gifts, and a year's worth of collectibles boxed. The only thing dirty about her hoard was the dust collection and the piles of random mice feces hidden between stacks of boxes. None of that was even known by anyone but those of us that were there to remove these items.
It can be hard to see when someone needs organizational help. Although there is the type of folks that just don't have guests come at all and that can easily throw a red flag. But those that are "organized" hoarders are hidden in plain sight. I pray that all of the people out there suffering from the weight of their clutter can forgive themselves. Hiding this part of their life is very painful and embarrassing. It can be hard to see even for themselves because they have spent so much time concealing the hoard. I can tell you that if you are this person or if you know this person the best thing you can do is start with a gentle push.
Perspective is everything. A hoarder is not always dirty. A hoarder suffers from their stuff as a weight around them. Remove with care & love.