I think the comments should be public but we should have the chance to view them first before they are posted. I guess you could do a drop down menu or a flag that would read "make comments public" Yes/no. If yes then get an e mail notice when someone posts a comment and have it where it does not show on the site until the owner approves it.
More than being a censor I want to know I am able to delte any comments made form people who want to sell me viagra, tell me the want to send me a check for 10 mil or want me to check a link for porno...seems these assholes have nothing better to do than clutter the internet...