When clients peel away the layers of clutter, they become more vulnerable. I sense sometimes that it's scary for them. The clutter has been acting in a way as their barrier from the world. I think they can feel unprotected as the walls of clutter start to come down. I know because I've felt that way myself when being clutter busted.
I've experienced an increased sensitivity, as if some kind of numbness evaporated. Everything become enhanced: my sense of touch, the awareness of things around me, and my feelings. I felt wide open. That sensation can be overwhelming at first. But I ride it out because I know after a short moment, I'll assimilate the tender experience.
When you're working by yourself, and you start to let go of things that no longer fit in your life, look for the greater sensitivity. It can help to expect the expanded openness. This can prevent it from being a shock. That's why I encourage curiosity while clutter busting. When we're curious, we're excited to see what we can find. Basically, we're finding ourselves.