Why do people say "kettle calls the pot black"?

Yes it is one of those stating the obvious things whereby both parties are of the same condition but one does not accept they are in that condition. Like the fatty boom bah saying the person next to him is a fatty boom bah. Maybe it refers to the 'olden days' habit of having a large pot over the fire place, which was generally iron which is dark. Older teapots were made of iron as well, so both are black or dark.

Make sense?

In days gone by kettles and pots were heated over a fire, the bottom of them would be covered with a coating of soot (carbon) fron the dirty naked flames touching them. Because they were both heated in the same way and were BOTH blackened from this usage, the metaphorical analogy has been carried over to mean hypocrisy as you have correctly inferred. So what it means is if for example 2 people are really loud at talking and one turns to the other and says " keep the noise down, you are very loud " the other person could say " eh, the pot is calling the kettle black ", meaning they are BOTH loud. A variation of this analogy is that only pots are blackened by the flames as 'some' kettles were heated over coals that did not cause the blackening and therefore remained shiny. So the pot would accuse the kettle of something because it saw its on blackened reflection in the shiny kettle, the kettle would point out that it was the pots 'own' reflection and therefore it was wrong (when in fact they are both wrong).

EDIT - ***Caitlin*** has got the origin incorrect, the material used is irrelevant, not all pots were made of cast iron and for good reason, it is brittle and susceptable to cracking ! Other metals were used that were not black at all...

The origin is what I say...

because of the fact the two are black and while 2 people criticize one yet another for a high quality that the two have, then this is the pot calling the kettle black. to illustrate if individual A calls individual B a slob yet individual A has an quite messy residing area packed with bacteria, that often is the pot calling the kettle black.

well, as I understand it, when this saying came into vogue, people used to cook over the wood stove and everything was blackened with soot. So if the pot called the kettle black, then that would mean the pot was being hypocritical because it most certainly would be black also.

The expression is actually "the pot calling the kettle black" and this means just what you think it means. It is a person that is being hypocritical. The origin is this: Pots used to be made of black cast iron, so when the pot calls the kettle black (regardless of what color the kettle is), the pot is being a hypocrite because it is black itself.

I hope that helps!

It generally means a contradiction. ie: That woman over there is very fat she needs to go on a diet. When the person who said it is 'fat' herself.

Some kind of drug reference... I used this phrase to score pot in Atlanta by uttering it to blacks wearing hoodies