I would say that bashing someone is making ugly, unkind remarks about them. I think negative remarks are somewhat different. If I said 'I think Prince so-and-so is a total jerk and ugly to boot and everything he does is wrong and stupid' then I would call that bashing. Perhaps, this is my point of view but that is what I consider to be bashing. If I said 'I think Prince so-and-so is not terribly nice, he's not my cup of tea, and isn't always prudent in decision making' then that would be more of a negatively tilted personal opinion. It's all in how one words something, imho.
I'm sure my fellow admins and moderators will have some very good answers as well. :)
It's clever, but is it art? ~Rudyard Kipling