To really appreciate the difference between professionally photographed, lit and edited properties, see the pictures below.
Replacing the sky on an overcast and cloudy day is a great tip for property photographs - though it requires some specialist skills to produce a realistic swap.
Non-professional interior images like the ones in the left column, are shot from head height, and so have an awkward composition and non-parallel vertical lines which are discomforting to potential buyers.
They also have inaccurate colour casts and areas that are either too dark or too bright, as despite their technology, even DSLR cameras have no-where near the dynamic range of the human eye, so they can either see all the bright areas, or all the dark areas, but not both.
Finally, you can see the difference when the mess and clutter is removed to reveal more of the design and layout of the kitchen.