Following up this old thread with vim highlighting the whitespaces in red, this did not work anymore in recent debian releases, now shipping >7.1 as versions. I never really cared about that non-functionality since git diff always worked showing bad code style.
Until now, when things become annoying. The reason is simple – the highlight match does not seem to work anymore, but luckily there’s a new possibility mention on the vim wiki. I prefer to have it system-wide, you may just use vimrc.local or $HOME/.vimrc
# vim /etc/vim/vimrc highlight ExtraWhitespace ctermbg=red guibg=red match ExtraWhitespace /s+$/ autocmd BufWinEnter * match ExtraWhitespace /s+$/ autocmd InsertEnter * match ExtraWhitespace /s+%#@<!$/ autocmd InsertLeave * match ExtraWhitespace /s+$/ autocmd BufWinLeave * call clearmatches()
Having that fixed, removing all trailing whitespaces at the end is tremendously easy too