Although you can clean a surface till it shines like a mirror, it can still be home to millions of germs. Most cleaners are designed just to dissolve grease or be an abrasive compound, but they don't kill disinfect and kill germs.
You could say that the mere action of rubbing a surface and drying it will in itself get rid of many harmful organisms, but it still leaves plenty of germs behind. However, a disinfectant actually kills microscopic bacteria and virus-carrying organisms.
There are a few ways to properly disinfect your surfaces each have their pros and cons.
Boiling water kills germs. You can buy a hand-held steam machine and use pressurized steam to blast through grime and germs. It works very well, but it isn't good for all situations or surfaces (ex. The high steam also peels paint).
The simplest way you can kill germs is by using cleaners with built-in disinfectants. The best ones kill 99 per cent of harmful micro-organisms. Spray all the high-risk areas in through out your home. Just remember though, they don't kill instantly. Leave the solution on the surface for as long as recommended in the instructions (usually three to five minutes) or else, you're not disinfecting, you are just cleaning.