One of the most common worries for people starting business blogs is whether they will get negative comments. Darren Rowse at ProBlogger wrote a good post about blog hecklers last month, and it’s worth reading. He does a nice job separating out the types of negative comments you might get.
I wouldn’t call all negative comments “heckling.” Someone might have a negative comment because they had a horrible experience with your company or product, and so when you write about those things, they disagree with your take on them and are going to tell you. This will probably happen less often than you expect, but it will happen, and that’s part of blogging. (It’s also an excellent chance to get some very honest feedback and you should listen to it and learn from it.)
But there are those people who really just want to be disruptive. So while you must be ready for negative comments, and you should not try to hide from them (or hide the comments themselves), it’s perfectly legitimate to uninvite a true heckler from the conversation.
If you don’t, they will tend to take over your comment threads, and the results will be a less useful blog for you - and for the other readers who do want to hear what you have to say and engage in conversation with you. Be judicious, give people the benefit of the doubt a reasonable number of times (sometimes tempers get hot online), but when it’s clear someone’s just trying to disrupt things, it is perfectly fine to block their comments.
As for plain old negative comments: you should look forward to them. They’re not always fun to read, but these are people bothering to tell you how you’re falling short. As I said above, listen and learn.