Wasn't sure how to answer this one, really.
When I'm building for upload to the Gallery, I put in very little decoration. I furnish them so a new family can move right in, not like they have lived there many years. When someone buys a new house, its not chock full of stuff, not even furniture or appliances.
If I build for my sims to live there, they have what they need to take care of themselves, and of course objects for skills. The house will be decorated as time passes by, with paintings and other small objects. I use alt-placement instead of MOO, which will let me place things more freely, but still with limitations. Mostly for garden plants and decoration.
I avoid houses on the Gallery that are decked out in clutter, or builders that use MOO. I end up deleting most of the stuff and re-arranging furniture/rooms, and that takes more time than looking for/building a new house.