According to the help, without -x option git clean should let alone the ignored files, but it doesn't.
[il@reallin test]$ cat .gitignore
*.sar
[il@reallin test]$ mkdir -p conf/sar && touch conf/sar/aaa.sar
[il@reallin test]$ git status
# On branch master
nothing to commit, working directory clean
[il@reallin test]$ git clean -df
Removing conf/conf/sar/aaa.sar is removed.
I already asked this http://stackoverflow.com/questions/23148736/git-clean-removes-ignored-files-by-default
Someone even replied that "git does exactly what documentation says". Well, maybe, but I have doubts that the combination '-df' (without '-x') is useful at all. If someone wanted to delete ignored files, he would use '-x' or '-X'.