Some of the trickiest “false friends” are adjectives which describe people’s characters. There are many of them that nearly mean the same thing, but not quite. A good example are the words “ambitious” versus “amibicioso”.
In Spanish “ambicioso” has a general sense of material ambition, more akin to the idea of acquisitiveness. A person who is “ambiciosa” is someone who wants a bigger house, a better paid job and more material possessions. Therefore, in many people’s minds the word has a negative connotation.
This materialistic element is included in the English idea of “ambitious”, but more generally in the English speaking world to be amibitious is regarded as a positive quality – a desire to better oneself, to get somewhere in life, to have motivation and commitment.
That’s the interesting thing about “false friends” – they can be very subtle, and they can create subtle misunderstandings!