Often what happens is some good things get buried in the clutter. They can remain buried for years. Either the person forgets they even have these things, or they remember and get frustrated that they can't find them. In either case, clients get excited when they discover valuable things. It's like an archaeological dig under the snows and ice of the frozen tundra when scientists uncover a wholly mammoth and get very happy.
A few years back I was helping clutter bust a client's junk cluttered garage. Most of it was trash and ended up in a dumpster. About halfway into the job, underneath everything I found three crates. We opened them up and it turned out they were actual Picasso paintings. He couldn't believe it. He'd forgotten he purchased them many years ago. Even I was excited. I actually touched real live Picasso's!
The treasures aren't usually that amazing. But they mean something positive to the person who finds them. They take many forms. Sometimes people find cash and savings bonds ($20,000 on the bottom of a box in a garage). Other times they find important legal paperwork. They can even be something as simple as finding an article of clothing they love to wear but had given up as lost.
This weekend I was working with a client to help her clutter bust her long ignored basement storage area. She couldn't believe that she didn't need most of the stuff we came across. We filled about ten bags for charity. But the thing that got her excited had to do with her business. She had taken twenty years off from a successful business to raise her kids. She wanted to start the business up again but was feeling resistance because she had lost all the tapes and writings that was a major part of her career. Lo and behold they showed up under the clutter. She was giddy!