Above kitchen cabinets and ledges: Try going higher than eye level and look at the top of the kitchen cabinet or on top of any ledges. Dust and cooking oil fumes sure do make a 'sticky' combination and you will find plenty of those there.
Around and on switchboards: A surface is not just dirty if it looks dirty. You need to be more regular at cleaning up switchboards simply because people touch switches regularly making them ideal places where germs are deposited and picked up.
Around exhaust fan: Your kitchen and/or bathroom exhaust fan blades are cleaned once in a while, but what about the area around the exhaust window? We bet you would find a thin layer of grime (dust and cooking oil fumes) that is sprayed outwards by the blades.
Above Geyser: Your storage type water heater is such a useful thing. But what about the top? Take a look and you will find layers and layers of dust that have been accumulating unchecked for years.
Above tube lights/ light fixtures: Just because lights are bright does not mean that they are immune to dust. Tube lights and high up light fixtures are perfect dust catchers that are mostly ignored during a cleanup.
Behind paintings: Paintings are supposed to make your living space look pretty. But then they hide a lot of wall and are also places where dust accumulates unnoticed. Make sure you remove paintings and wipe out the dust on a regular basis.
Behind sofas: There is something very wrong with sofas when it comes to cleanliness. Positioning them next to walls creates a small gap inaccessible to brooms and mops. It is pretty hard for the regular home owner to shift the sofa for cleaning this gap.
Above air-conditioner voltage regulators: You clean the top of your window or split air-conditioner but what about the voltage regulator that is mounted nearby?
High windows: You never clean those high ventilator windows.
Under the sink: Your shiny well scrubbed sink is keeping a dirty secret. Check out it's under side and all will be revealed.