[twic]

I am one of the handful of people to use a white background in my terminals. A significant amount of coloured output is illegible to me.

I would suggest these rules for using default coloured output:

1. Don't.

2. Really, don't. Bold is fine, though!

3. (experts only) Make sure the colour scheme works with white-on-black, black-on-white, white-on-navy (for powershell), and Monokai/Solarized/whatever the flavour of the month for insecure hipsters is.

If you use colours, by default or not, make it really easy to configure the colours, so people can make it work with their terminal's colour scheme.