There is always some publicity that is bad, for example if you have a very bad product malfunction or error such as mouse turning up in a cheeseburger, and the company just has to resolve it pro-actively as possible.
The key question revolves around publicity that could be seen as negative by some people (but not all). The general rule of thumb is that the larger a company is the more carful it has to be of this type of publicity as it has less to gain and more to lose. Conversely a smaller firm will be more likely to benefit. This is why you are more likely to see controversial PR stunts, or more extreme positions held, by smaller firms. It is also why many smaller firms will target a larger firm to have a "battle" with, for example over a copyright issue, as they will gain more from the resulting coverage. It is a challenge for a smaller firm to be able to maintain this edginess as it grows, not just through publicity but though all of its actions.
I hope you find this useful information.