When I linked to one of my on-line dating blog posts on Facebook, a friend commented that she wished dating sites would allow people to review users after meeting them in person.

Though I understood her thinking, I demurred, citing a list of reasons that an on-line date-rating system could go wrong.

And then I saw an article in The New York Times about Lulu, a Facebook app that gives users a platform on which to anonymously review the men they know.

Alarm bells.

Problems rampage through other on-line reviewing systems. A myriad exist: Amazon (of course), Yelp, Citysearch, Glass Door. And so on. Even Facebook has a business-review component. Also, most e-commerce sites allow users to review their wares.

Great, right? Yet rather quickly, researchers exposed fraud on these sites:

• People post negative reviews to take revenge. (And imagine how this could play out on a site allowing people to review other people, rather than companies, products, and services.)

• Business owners and employees and company devotees post false reviews to cast negative light on competitors.

• Companies hire review “farms” to blanket the Web with fake reviews (positive for their products and negative for others’ offerings).

Even actual reviewers skew results. People tend to write reviews only when they have over-the-moon experiences—or really negative ones. The happy middle—typically the vast majority of consumers—don’t bother.

I put far heavier weight on reviews written by professionals published in legitimate, edited publications over on-line reviews from anonymous or unknown people. And when it comes to review-site results, I cull details on a place, product, or service and mostly ignore the reviewer’s take on the item. (What sort of atmosphere will I find? How about amenities? How does the product function? What kind of plot or theme does the book present?)

Do you trust on-line reviews? How do you use them?