What does show one's true colors mean?
I believe it's a naval idiom (like many others); colours = flag. A pirate ship would fly a neutral flag until it got within firing distance, and the 'reveal its true colours' [break out the skull and cross-bones].
I came across this phrase in a video about Dixie Chicks. Someone said 'Dixie Chicks showed their true colors by saying that they were ashamed of US president for launching the Iraq war.'
I'm not sure if this is commendatory or derogatory.
they have revealed their real feeling about usa.
Background - fyi
Just found this: http://ccwf.cc.utexas.edu/~banks/ima...olly-roger.gif