Yeah, that's all it does is tell you how many rows were affected, but they should be gone now. Hopefully those were the correct messages, but unfortunately there's no way to know without looking where they used to be. I guess you could look around and make sure everyone's vistor messages look OK.
You could do this:
Code:
SELECT * FROM visitormessage WHERE postusername = 'username'
and if you get no results, then you've succeeded.