Please Stop Review Farming
Example video of how farming happens: https://9gag.com/gag/aGdrew5
Please note the video may perhaps be fake. But the practice of farming is not impossible.
I use words such as, product, review, buying, etc. But their meaning might change upon context. For e.g. apply the context for this site...
Note: I am not pointing fingers at any online applications or services.
How to stop this?
The consumer cannot do much. He or she, at best, can perhaps report the comment or review. Provided the consumer can spot it.
It is up to the concerned enterprise to investigate and take action. Else they are going to lose the trust of customers. I am highlighting a few approaches.
(1) IP address analysis.
If all reviews to some product comes from one ip address, we can take some action. This is simplest of cases to expect
(2) Study the user accounts.
(2.1) If there are a few accounts with the same creation date, and, those same accounts have not much review history...you can investigate and arrest the actual owner of that user, or, more practicality, ban the user.
(2.2) What if there is a geography separation? Find out if the user has frequently changed geographics. This ties into point #1.
(2.3) Suspicious user. Mostly they won't have a photo, bio, etc. A relative air of anonymity is a red flag, but, requires more investigation.
Final notes...
I could only highlight a few approaches. But I think a better proactive approach is to delay the reviews as such - and then run those analyses, cleanup, and, release them.
"Farming" indicates a bigger social problem exists. Hoping you can expand what more can be done here. Its actually more complicated than it looks.