I’m getting an error 401 when I call GET statuses/user_timeline for an invalid (suspended) user. I just switched to application authentication, and since error 401 is invalid credentials I thought I had done something wrong. But all other queries seem to work OK, so I think it is because of an invalid screen name in the call. I appreciate this use case is not high priority, but you might want to check to make sure the root cause isn’t causing more dire problems elsewhere…
Turns out the same problem happens with traditional OAuth 1.1 user authentication…so it’s not an auth style issue.