bash-it themes must not set the TERM variable. The used terminal emulator is responsible to set this variable correctly.

themes/sexy/sexy.theme.bash

@@ -2,10 +2,6 @@
 # Screenshot: http://cloud.gf3.ca/M5rG
 # A big thanks to \amethyst on Freenode
 
-if [[ $COLORTERM = gnome-* && $TERM = xterm ]]  && infocmp gnome-256color >/dev/null 2>&1; then export TERM=gnome-256color
-elif [[ $TERM != dumb ]] && infocmp xterm-256color >/dev/null 2>&1; then export TERM=xterm-256color
-fi
-
 if tput setaf 1 &> /dev/null; then
     if [[ $(tput colors) -ge 256 ]] 2>/dev/null; then
       MAGENTA=$(tput setaf 9)