How should we moderate comments on our company blog?

A surprisingly simple (but also quite tricky) question, that Jacob Morris asks over at Delta’s new blog.

Should any comment be allowed that people feel is relevant? Should vulgarity and ad hominem attacks be deleted? Or should comments have to be relevant to the post’s topic and express some sort of constructive argument, as oppossed to “Delta sucks, because I missed my flight”?

Have a look at the comments for the entire range of opinions. My impression is that the consensus seems to be don’t delete comments based on how unflattering they are. I’d say that doesn’t necessarily mean irrelevant posts are okay – a comment can be relevant to the topic and either positive or negative, or it can be irrelevant (off-topic) and either positive or negative. Of course relevance is a tricky concept altogether and one is much more likely to discard a critical remark on the basis that it’s not really relevant than one is to delete praise. I’ve deleted lots of spam comments lately that said things such as “I really like reading your blog” or “Great post!” and the author conveniently provided the URL of a site where you can purchase bootlegged software or pills that supposedly enlarge certain organs. The premise here is: flatteries are less likely to be deleted, even when they’re grossly off topic.

But how should corporate bloggers deal with off-topic comments, assuming they are written by humans and without the intention of selling Viagra? I think that a successful corporate blog should enable open discussion, but not venting or rambling. Not because those things are somehow inherently bad, but because they only benefit the person venting or rambling – neither other readers nor the owners of the blog really learn anything from contributions like that. Comment is free on the Net and anybody who feels the urge to get it out there can do so on his own blog. But I wouldn’t allow something that fulfills a function only for the commentator and not for anyone else (which is the case in such cases of trolling).

I’m curious, what’s your take on this?