Marshall - 4:12 pm on Dec 8, 2011 (gmt 0)
"Reviews" are not a "trick" but an important part of customer relation management
Maybe "gimmick" would have been a better word. I worked for an ad agency for a while, they're all gimmicks. The best one was "lather, rinse, repeat." The addition of that one word on shampoo increased sales over 50%.
In B&M stores you also have word-of-mouth recommendations. Online reviews are pretty much the same.
Most word-of-mouth recommendations are neighbors, friends and family, people you personally know. Posts are anonymous so it is nearly impossible to know if they are genuine or not.
But again, the OP is about the ease to skew these results, not the merits of their existence.