equokka That's it, managing other people's clutter! The people we know are, like so many people of course (so it's not a horrible criticism or anything), the kind of people who hold on to a lot of stuff because of "What if...?", or because they feel sentimental, they feel they need to hang onto things given to them, because they feel like they're losing money to get rid... and so on. So sometimes they give us things that we don't really need or want, and when we attempt to return they'll say, "Oh no it's okay, there's not rush" and I've started to realise that it's easier for them, because it gets it out of the house, but without having to properly get rid of it. Especially when they tell me about how they need to declutter, and how difficult it is to sort things out. It has taken us quite some time to get to the point that we're at now, and I still think there are bits here and there, but nothing overwhelming anymore and it's all a lot easier. So our friends/family are now asking us about how we did it, and when we talk you can see the mental process, the same that we went through, of trying to work out if you can really let go.
That might be a bit waffly 
But yes, sometimes it's weird how you end up managing their clutter for them. I think it's similar to how some people put things in storage, even for years, just so they don't have to give things away. I can understand if you have very little space, and maybe some family heirlooms or treasured items that you want to hand down to children and not just sell or give away, but I know people who are filling storage units with Ikea furniture and boxes of random papers and such just so they don't have to let go but to get it out of sight.