I have a request and this comes down to fair representation and comment; I'm not going to shut down debate or even negative comments on my blog. I post things and you guys can throw rocks at them but...
I think it is only fair that I know who is throwing the rocks! So if you work for a vendor or a reseller of a particular product, I would like you to use your work-email address or link to your company's website. Or just declare it in your comment. If you don't want to reveal your work email, drop me an email to email@example.com to declare and I'll be happy.
Put like this, bloggers have to declare their interests and pretty much all of them do; I think it's only fair and courteous for the commentators to do the same. It doesn't invalidate your views but it allows context. And I'm not going to out you as working for company 'A' or company 'B', most of the time it is fairly easy to tell from the tone of the comment who you work for.
Still, I would say that in general if you work for a company which sells a particular product, you should be proud of that product and should have nothing to hide. If you think the company you work for wouldn't like the comments you are making, I'd suggest you think twice before posting them.