The best defense is a good offense.
You can't control what other people say or do, but you CAN take control of your response.
As tempting as it may be to ignore the negatives that sometimes appear online about you, many times, that is not a wise course of action. This doesn't mean to be reactionary either. Engaging in a verbal debate in person is one thing - preserving that fight on the internet, in print, forever, is another. In short - don't do it!
Rather, take charge with an intentional brand strategy. If there are legitimate issues to be addressed, address them in the appropriate forum. The rule of responding "like with like" applies. If you are criticized in Twitter, responding in Twitter would be the way to go.
Overall, though, taking a more positive approach is a better strategy. As most people don't look beyond the first page of Google (and rarely beyond the third), work with AVS to develop a strategy to keep your positive postings front and center. Make sure your positive story doesn't get lost amidst the negative and nay-sayers.