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Oh boy that is a tough one. Even for me, and I have done it!

Look at the reviewer. See what else they have written about other products or businesses. Still it can be hard, but sometimes you can tell. Like if the profile picture is of a girl, but the products are not in line with what a gal will buy. Or if the image shows a 20 year old guy and the purchases lean toward a geriatric style.
Or if you see on Yelp that the reviewer lives in San Francisco, but wrote about a painter in Austin yesterday and a home decorating company in Chicago last week. You can spot the professional review writers easily that way. But still, some are clever and have a number of accounts and keep track.

Good question!

Wow, some people are too creative for their own good

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