If a 5-star review is posted on both Google Local and Yelp (identical review text), does it affect the SEO in a negative way (duplicate content or anything else I may not be thinking of)? Or is it a positive, in the sense that there are now two positive reviews out there? To clarify, I am using Google and Yelp as examples, my question really applies to all review sites.
The googlebot crawler is intelligent enough to identify situations where content may be duplicated for a reason, they already do this for product pages where the exact same text is present on a range of sites selling the same product. In addition the page taken as a whole will be different from the other customer ratings sites due to different customers adding ratings on different sites.