The python script eFindStaleFiles.py recursively traverses all directories given to the script for files or directories that are not tracked by portage. The blue output is debug output on stderr.
After downloading you may try the following:
The former version of the script did also traverse content of non-tracked directories and it followed symbolic links. The new script, however, fixes this. (It was annoying that the symbol link /usr/lib to, i.e., /usr/lib64 is fully traversed and all its content is reported as untracked.)