Spammers excluded, of course. If you aren’t going to comment, then what’s the point of signing up as a user? I have a plugin that catches spam comments, so that is not a reason. In addition to the plugin, I moderate ALL comments before they are published on my site, so whatever the plugin doesn’t catch (and that’s very little), I do.
I’m looking for really sincere people who actually get something out of what I’m posting.