dark blue text unreadable in black background
green text readable in black background
On Debian systems (and perhaps on other linux distros as well), the foreground color of comments is blue by default. This looks quite unreadable on black background, which is the case for most terminal windows.
As you can see, the above is quite unreadable. But the fix is quite simple. Let's say you want to make all comments show in 'green' instead. Just add the following line to your ~/.vimrc (or /etc/vim/vimrc.local if you want to change it for everyone on your linux box).
highlight Comment ctermfg=green
Now the colors look far more readable. See below.
