apt-get update output on the lines with a 403 error:
W: Failed to fetch https://private-ppa.launchpad.net/commercial-ppa-uploaders/bit-trip-beat/ubuntu/dists/precise/main/binary-amd64/Packages The requested URL returned error: 403 W: Failed to fetch https://private-ppa.launchpad.net/commercial-ppa-uploaders/bit-trip-beat/ubuntu/dists/precise/main/binary-i386/Packages The requested URL returned error: 403 E: Some index files failed to download. They have been ignored, or old ones used instead.
Here's what's in
cat /etc/apt/sources.list.d/*.list | grep ppa:
deb https://private-ppa.launchpad.net/commercial-ppa-uploaders/bit-trip-beat/ubuntu precise main #Added by software-center; credentials stored in /etc/apt/auth.conf
Here's a redacted version of my auth.conf:
machine private-ppa.launchpad.net/commercial-ppa-uploaders/bit-trip-beat/ubuntu login dlamblin password 3..................6
That's a hash presumably for the purchase processed through my Ubuntu One account for the Humble Bundle for Android 3 (and Windows/Mac/Linux).