Interesting article. I review on Amazon & get a lot of offers of free stuff. I tend not to get items that are pretending to be a brand name, but I do get items of varying quality made in China.
I’m always honest about poor items. I’ve given 1, 2 and 3 star reviews many times.
This doesn’t stop the free stuff from coming at all. A few sellers have asked me to change reviews; I’ve refused.
I only ask for stuff I think I will like that I will use myself. So a lot of my reviews are four or five stars; not everything I receive is poor quality.
A lot of reviewers automatically giving five stars to an item have had their reviewing rights revoked by Amazon.
There are threads about this on the Amazon forums.
I live in the UK but I have also posted reviews on Amazon USA.