I'm a checker of reviews and ratings. If I hear about a book or movie that sounds interesting, I'll look up more information on it before deciding to see or read it. If I need a new toilet, even though I may be impressed by American Standard's Champion model -- which can evacuate 29 golf balls in a single flush -- I'll still check to see which toilets Consumer Reports recommends.

Thus, it's not surprising that on occasion, when I find myself at the Morningstar website looking up some esoteric information on a mutual fund, I find myself swayed by funds that have earned five-star ratings.

I recently ran across an interesting article, though, that has tempered my enthusiasm for five-star funds. Penned by Morningstar's own director of mutual fund research, Russel Kinnel, it candidly explained that the quantitative nature of Morningstar's rating system invariably includes some duds on occasion, and "therefore does not serve as a substitute for fundamental research."

Crossed stars
Consider this scenario, for example. A fund invests heavily in some sector or nook, such as energy stocks or emerging markets. If that area has been on fire recently, the fund might have achieved amazing results in the recent past, making it look better in the eyes of the star-rating system. But hot areas inevitably cool off.

Similarly, a terrific fund might lose its top manager or managers. It won't show up in the ranking, but there are few changes more significant for a fund than the loss of its leadership.

As one example of an overrated fund, Kinnel pointed out the five-star Jacob Internet Fund, saying:

This fund is a classic example of the quirkiness caused by the time periods that factor into the star rating. Investors who bought at inception are still about 70% in the hole, yet this fund still has five stars because its horrific bear-market losses are starting to roll off the five-year record. The fund's 79% loss in 2000 isn't there, and its 56% loss in 2001 is starting to fade.

Kinnel also cited its very high expense ratio (annual fee) of 2.64% and its "unimpressive manager."

In the fund's defense, I'll point out that its past few years of returns aren't so shabby: 101% in 2003, 32% in 2004, and 10.8% in 2005. Still, there are less risky ways to make money in mutual funds. (The fund's top holdings recently included News Corp. (NYSE:NWS), eBay (NASDAQ:EBAY), and TD Ameritrade (NASDAQ:AMTD).)

Go beyond numbers
It's easy and tempting to find promising investments simply by running quantitative screens. For example, I looked up S&P 500 component companies with profit margins of at least 20% and betas of no more than 1.0. That should give me stable, high-profit firms, right? Well, it will. The screen turned up Medtronic (NYSE:MDT) and Pfizer (NYSE:PFE), both of which have many fans -- though Stephen Simpson has his doubts about Medtronic, and Pfizer stock has been languishing for years (trust me, a shareholder, on this).

The screen also included many less attractive firms, such as energy concern Kerr-McGee (NYSE:KMG). It's a company that looks good in various measures, but since it's being bought by Anadarko Petroleum (NYSE:APC), the share price already jumped considerably on that news.

Look at the big picture
So when you're prowling for stocks or funds, make sure you look at a lot of factors, not just a few. Focus on both the quality of the company (including profit margins, revenue and earnings growth, return on assets and equity, free cash flow, and competitive strengths) and on the stock's price (including the P/E ratio, market capitalization, and discounted cash flow analysis). Include qualitative factors as much as possible, too, such as the quality of management. With mutual funds, assess the long-term track record of the managers, as well as the fund's focus, its fees, and its communications to the public.

That's what Shannon Zimmerman does when he seeks out terrific funds with outstanding managers and reasonable fees, then recommends them for our Motley Fool Champion Funds newsletter. Try it for free to see which funds he has recommended -- and why. Together, his picks (as of the last time I checked) have more than doubled their benchmark's returns, gaining an average of 17% versus 8%.

Learn much more in these articles by Shannon:

This commentary was originally published on June 2, 2006. It has been updated.

Selena Maranjian enhanced her home with doormats and curtains. She owns shares of eBay and Pfizer. Pfizer is an Inside Value recommendation. eBay is a Stock Advisor recommendation. The Motley Fool isFools writing for Fools.