One of the best qualities of the Internet, and one of the worst, is the evaluations of products and services you can read on it.

In the past, to make an informed buying decision, among other things you could do the following: check with the Better Business Bureau; read Consumer Reports' articles and surveys as well as reviews in professional or trade publications and newspapers; ask around among your colleagues, friends, and family; rely on your own previous experience; and use the information from ads.

Today, you can still do these things, and you can also read on the Internet about the experiences and impressions of fellow consumers. But you have to be careful.

Critical thinking is a skill that has been taught in educational institutions since the time of Socrates in ancient Greece. Trying to determine the validity of information today, especially information available over the Internet, is more important than ever.

It's as easy for a user of a product or service to put up a legitimate review on the Web as it is for the company behind that product or the public relations company it has hired to put up a fake review extolling it and/or condemning a competitor's product.

A lot of people get snowed by fake reviews. Not long ago I almost got snowed myself by fake reviews of an apartment complex. I was able to conclude these reviews were planted only after careful scrutiny. The planted reviews nearly stopped me from moving in. A later discussion with the apartment house's manager revealed that a nearby apartment complex was likely planting these scathing reviews, and that the apartment complex I moved into was likely doing the same with the other complex.

Fortunately, large sites such as Amazon.com (www.amazon.com), Yelp (www.yelp.com), and Angie's List (www.angieslist.com) do a good job of weeding out the most blatant of these planted reviews and of making more prominent the reviews that can be trusted, those that others find most useful.

Still, fake reviews do make it through, and based on anecdotal evidence and on the attention this issue gets in the media and in academia, the problem of fake reviews remains serious.

Here are some ways to make the best use of the reviews you come across on the Internet:

* Discount reviews that are gushingly positive. Be wary also of stellar reviews that include only a minor negative or a minor feature that's missing. These could be legit, or they could be planted by a clever paid reviewer.

* Likewise, discount reviews that are scathingly negative. Some reviews like this are so over the top that you could only conclude they were planted by a competitor or were otherwise written by someone with an agenda.

* Lean toward products or services that have received a lot of reviews. Conversely, be more careful with products that have only one or two reviews.

* Ignore reviews that describe the reviewer in too much detail. This could be a tip-off that a public relations firm is trying to target the demographic group represented by the reviewer's self-description.

* Discount reviews that are merely a list of features. The best reviews, whether written by an ordinary user or a professional, indicate the benefits you can derive from using the product. Consider those core features you'll actually use rather than fancy features you probably won't.

* Similarly, pay more attention to reviews that compare the product or service to similar ones. The best reviews put a product or service into context rather than just talking about it as if in a vacuum. Comparative reviews also indicate that the reviewer likely has more experience with the area and can be more relied upon.

* Don't be swayed by reviews that include a lot of impressive-sounding jargon. This may indicate the reviewer is just trying to impress others, though depending on the product or service, some jargon may be necessary for a full evaluation.

* Look for commonalities. If a number of reviewers offer the same opinion about a quality of a particular product, this gives the opinion more validity.

* Ignore reviews that sound too much like other reviews of the same product. This could indicate that they were written by the same person.

You can help with the online review process yourself by writing informative, comparative reviews that describe benefits in easy-to-understand language. You can also participate in whatever system the particular website uses to rank or legitimize the reviews of others, such as "Helpful" votes with Amazon.com.