When is it appropriate to remove a comment?

As I do more interviews and discuss the Web with people in my travels, one of the questions that people ask me for advice on is when is the right time to remove a comment. Now I am sure half of you reading this article will say, "Never" and the other half will say, "Anytime you want."

My belief is that there are some limited circumstances where removing a comment is appropriate because everytime you remove a comment that is not one of the below items, your trust level may become questionable. Here are my thoughts:

• Spam - if the person is posting about penis enlargement on a site about iPods, this should be removed
• Illegal activity - duh.
• When a comment is clearly causing a fight not related to the topic

When should a comment not be removed:

• Just cuz.
• When the comment calls out the writer of the article to explain where they came up with some figure/statement
• When the comment calls the writer's integrity into question

I have seen many posts on the "big Web 2.0 boards" which call into question the site owners accountability for the posting. Yet somehow those posts are removed later in the day. But yet, posts that compliment the writer stay. And I do believe that a site owner should/can do whatever they want.

But when you remove posts that contradict what you say, call you out to explain something, then your trust factor declines. And over time, if enough people do not trust you and your posts, they will go elsewhere. Even if you are the biggest today, when your customers (that's what users are btw) question your ethics and trust level, they will eventually leave.

So I call out to the current leaders of the Web 2.0, both product and news sites, think before you remove. Your trust ranking is at stake.