I rarely use much clutter - it causes issues usually, especially if using MOO. I especially avoid shelves with stuff on them because with walls down, it often looks like stuff is floating. I prefer sims houses to be functional and I also don't like when they get overwhelmed with happy moodlets due to so much décor. I love a lot of the builds on the gallery, but I stopped using them for the most part because they use MOO and have way too much stuff that causes issues or blocks my view. I am not a great builder, but my houses do function! About the only time I use much clutter is if I want to be sure a coffee table or desk does not have any usable slots left for sims to put all their dishes on!