UTF-8 in Terminator

Inside a terminal emulator that supports UTF-8, you can use the luit command to run a subshell (or other program) in a different locale. The locale setting that indicates character sets is LC_CTYPE.

LC_CTYPE=ru_RU.KOI8-R luit ls   # run one command
LC_CTYPE=ru_RU.KOI8-R luit      # start a shell (type Ctrl+D or exit to return to the parent shell)

If you have a whole tree of files in a different encoding, I recommend (if possible) mounting it through convmvfs.

mkdir ~/net/ivan@example.com.KOI8-R ~/net/ivan@example.com.UTF-8
sshfs ivan@example.com: ~/net/ivan@example.com.KOI8-R
convmvfs -o srcdir=~/net/ivan@example.com.KOI8-R,icharset=KOI8-R,ocharset=UTF-8 ~/net/ivan@example.com.UTF-8
ls ~/net/ivan@example.com.UTF-8

Your setting for LANG must match the terminal's. More precisely, your setting for LC_CTYPE (the character encoding) must match the terminal's encoding, the other locale settings don't need to match. And the terminal's encoding is usually specified by an option of the terminal emulator and not by a locale variable. The LC_CTYPE combines two indications: it tells applications what encoding to use on the terminal (both for input and output), and it tells applications what encoding to use with files. In cases 2 and 3, you've told ls to display output in an encoding that's different from the terminal's, so the output is garbled.

If you work with both UTF-8 and latin-1 encodings at different times, configure your terminal to use UTF-8. This should cause it to set LC_CTYPE to a value indicating UTF-8; don't override this setting. (If the terminal emulator doesn't set LC_CTYPE, do override it in your shell startup file or for your whole session.) To work with latin-1 data in an UTF-8 terminal, use luit (included in the X utility suite).

LC_CTYPE=en_US.iso88591 luit

(You can use any other locale with the same encoding, e.g. LC_CTYPE=es_ES.iso88591 luit.)