I've seen good and bad, myself. I have a mental list of some people that I will never have business dealings with due to how they've conducted themselves on internet BBs. As such, I likely wouldn't have known about them or had any negative connotations with them if it weren't for these BB posts.
By the same token, I have met people (well, I've truly met, and e-"met" people) that I would love to have business dealings with, and I likely wouldn't have known about them if it weren't for BBs.
I really, truly think that if you associate your business with your BB profile, you're always "on stage." What you say is going to affect how the internet community perceives you, and it may affect your business one way or another. What you say and post about can affect a person's perception of your business in the long run.
I do find it interesting what some people will or will not post about when (or perhaps in spite of or due to) having a business linked to their BB profile. Is it a case of "any press is good press as long as they spell my name right?" Is it perhaps "if you don't like what I have to say, then I don't want your business anyways?" Or maybe even just "barn blindness" (for lack of a better term) separating business from "pleasure" (again, excuse the term.)