You can add seller rating to your Google AdWords ads. Your Google AdWords ads might show seller ratings if your customer is searching on Google.com, Google.co.uk, Google.de or Google.nl.
Australian customers searching on Google.com.au (google australia) will have to wait for sometime to see seller rating in AdWords ads.
The benefit of seller ratings is that they let Google users know about advertisers who are rated well by their customers. This helps customers make more informed Internet-browsing and purchase decisions. And it helps you potentially earn more qualified leads, which in turn can increase your clickthrough rates.Google recommends, http://support.google.com/adwords/bin/answer.py?hl=en&answer=2375474
The best way to improve your ratings is to make sure that your customers receive excellent customer service. Happy customers attract more happy customers, who are willing to rate you well and tell others about your business or products.