What do you mean by "shady tactics to prop up positive reviews over the years"? I'm an employee and we have very strict policies around review fairness. If anything, most review-related complaints come from hosts who want to have negative reviews removed due to perceived unfairness. By policy, negative reviews are rarely if ever removed this way much to the chagrin of hosts.
Reviews are usually ranked chronologically, but in some cases there may be sorted by predicted relevancy ranking based on review length and language.
Reviews are usually ranked chronologically, but in some cases there may be sorted by predicted relevancy ranking based on review length and language.