I've been thinking that because of the same reason why women get insecure when looking at beauty magazine covers, we all get insecure and anxious about our houses when flipping trough interior design and decoration magazines. It's like "everybody" knows how to do it and sometimes it's not about money and buying expensive things, it's the whole aura of those houses, it's all so perfect and pretty, but how? Well I believe it's styling, there's no photoshop (sometimes in colours though) but pieces are moved, there's wine in glasses, fresh flowers and bowl of delicious biscuits. I mean, we drool for things that are not part of the house or decoration.
Some websites are getting famous for showing photos of more normal, cluttered houses but I guess there's a lot of staged scenarios in there too.
Take theselby.com, where you can see houses of creative people.