My thoughts, quick:
Some things that seem like vandalism aren't, they're user errors. That's why revert & warn is important - silent reverting is almost guaranteed not to affect the user's behaviour.
"indefinite" blocks aren't "infinite" - unless you go whole hog and protect the userpage. They can complain (if they dare to).
Sock puppets are a pest. However, false accusations of sockpuppetry are fairly common, and also disruptive & divisive. That's a problem.
Not thinking of anything more at the moment. --Alvestrand (talk) 21:21, 17 April 2008 (UTC)
"Everything that makes you reach for the rollback link." Really? This looks way too inclusive to me. Apart from many ways in which even experienced users could well produce a mess that cries for use of rollback, this exception also sounds a bit like "whenever an edit makes you angry" to me. I am sure it's not meant that way, but I am equally sure some people will read it that way. --Hans Adler (talk) 11:35, 18 April 2008 (UTC)
One thing I'm sure about from reading WP:AN/I on a near-daily basis for a couple of years: whenever someone defends themselves with an appeal to "Assume Good Faith", they are not acting in Good Faith. Especially if they refer to it by it's acronym. Which leads to the question, "How does one explain that they are misunderstood, that one is not acting maliciously?" My answer is simple: explain carefully, as if you were not talking to another Wikipedian. "I didn't know", "It was an accident", etc. carry a lot more weight with me than immediately demanding "AGF, please!" -- llywrch (talk) 19:20, 18 April 2008 (UTC)