I remember watching a news magazine show where they were discussing the different places in the house which has the most germs and is the dirtiest. They said that the kitchen sink is dirtier than the toilet bowl. Shocking! Well, this could be true if you do not clean your sink regularly, especially the kitchen sink. It is where all the food are washed and we all know that uncooked foods like chicken can harbor germs like salmonella. That is why it is very important to always wash and clean the kitchen sink at the end of the day.
If you have a stainless steel sink, you can wipe it down with a glass cleaner for make it shiny. This is of course, after scrubbing it with hot and soapy water.
One all-around cleaner I use is Borax. It does not scratch cast-iron, porcelain sink, stainless steel sink or even zero radius sinks. You can also use baking soda for cleaning and scrubbing the sink. With borax or baking soda, make a paste and scrub the sink with a sponge. For heavy stains, leave it for a couple of minutes before rinsing. I have a white porcelain sink and I use borax to clean it. It is still sparkling white after almost 8 years.