If you use Amazon product export tools or if you've done any work with Amazon's Product Advertising API, you'll have probably noticed that Amazon does not offer the rating of a product as a field that can be exported. One can only speculate as to why this would be the case, but the only information regarding the reviews of a product is a URL to an iFrame that gives you only a visual glimpse at the ratings and no way to actually use it for data mining.
In any case, I have found a way that you can use Google Sheets, in conjunction with a list of ASINs, to export and scrape the product rating for a given list of products. The number that is returned is the aggregate rating of the product. More specifically, it is the number out of 5 that the product is rated.
It is important to note, however, that Amazon is stringent about scraping and people have reported being blacklisted when doing this sort of operation too often. So it is best to use moderation when using this Google Sheets formula.
Amazon Product Rating Google Sheet Formula
This formula assumes that all of your ASINs are in the "A" column. So, to use this, simply paste this formula in cell "B1" and the reviews should start populating in that row. To use this formula among multiple rows, simple drag the bottom right corner of B1 down to the last row you want to process.
=left(JOIN( CHAR(10) ,IMPORTXML(CONCATENATE("https://www.amazon.com/gp/customer-reviews/widgets/average-customer-review/popover/ref=dpx_acr_pop_?contextId=dpx&asin=",A1),"/")),4)
Using this simple formula you can quickly gauge if a product is worth buying or selling. If you want to export more Amazon information with a Google Sheet, check out this guide on exporting Amazon prices with Google Sheets.