In Linux at least, if you want to use a temporary profile for testing an app or extensions with default settings, you don't need to muck around with the Profile

In Linux at least, if you want to use a temporary profile for testing an app or extensions with default settings, you don't need to muck around with the Profile Manager at all: mkdir /tmp/test-profile firefox -no-remote -profile /tmp/test-profile Browse around, do your testing, blow away the directory when you're done.