Having tabs and spaces visible as separate entities in vim is very neat feature especially if you use colors to differentiate.
Switch TERM to konsole-256color in kde konsole terminal emulator (or whatever emulator you use – rpm -ql ncurses terminfo | grep 256 for more) and put into .vimrc:
highlight TabGroup ctermbg=233 guibg=233
match TabGroup /t/
Now tab characters are a bit brighter than spaces.