I can find some bad reviews on items that have a lot of positive reviews on Aliexpress. Seems like they don't completely filter all of them.
If you read the aliexpress reviews, there are a lot of 5-stars totally bashing the product.
But they do have a time limit on leaving a review, as far as I can tell.
They have a 30 day time frame to leave a review. That's why so many reviews just say "Everything arrived on time" and none of them say "this thing broke after 31 days".
AliExpress highly encourages leaving a review. They also encourage taking pictures. As a result, loads of random pictures in reviews.
You can do an additional remarks later, but I often don't bother. It's drowned out anyway.
What I often do is read the reviews. What's usually done is a critical review and still 5 stars. The fake reviews are pretty easily spotted. It shouldn't be this way, but in my experience it's still better than Amazon. With Amazon more effort is made to fake a review.