Question about blog comments

Here's a suggestion that might help you find some middle ground:

Download and install 2 important plugins - Keyword Luv and Comment Luv. These 2 plugins give your readers an opportunity to "plug" themselves in a way you choose, without being disrespectful to your blog. If I'm not mistaken, you can also choose settings that allow commenters to post links and so on only after they've posted a certain number of comments. That way, they're kind of forced to contribute quality to the conversation and then they're "rewarded" by being allowed to add links and such once they've proven themselves to be worthy contributors.

Another thing to keep in mind, and some might agree with me but this is just my opinion...don't automatically frown upon your competitors posting comments to your blog, or automatically delete comments because they're from competitors. Often times conversation between competitors (as long as it's professional) can significantly boost seo efforts, search rankings and traffic to a site or blog. And you can use the opportunity to prove how and why you're better than them (again, in a professional manner). Customers ultimately win in this situation, as they get to check both you and your competitors out, see how you handle yourselves get more info to make their decision (whether buying or signing up). This was a very effective strategy for me in my early IM days, and the result were pretty amazing. I was even able to turn my "nemesis" into a reluctant supporter, which blew our sales through the roof.

But first and foremost, download those commenting plugins (you can get them from the WP repository). You might even want to try the plugin Disqus. You have to set up an account for it, but users have to log in using Open ID or one of their social networks and the conversation is spread across the web - which means they'll probably keep themselves in line to avoid looking bad to their own followers.

Hope that helps!