Nothing makes me happier in investing than getting a terrific dividend from a company. And with good reason. Time and again we have seen outsized dividends hold off sellers and stop declines. We have seen the power of reinvesting dividends to compound gains. And we know dividends have provided about half the return investors have gotten in the past decade, a dismal decade for investing. If you pick stocks with good dividends, you are on the right track to successful investing.

Ah, but here's the catch. It's the phrase "good dividends," because we have found that not all dividends are created equal.

Take the sorry case of Supervalu (SVU), one of the largest supermarket chains in the U.S. and a company that had told us over and over again that it was confident in its dividend and that it understood how important it was to shareholders.

Remember, when stocks go down, yields become larger, as the dividend stays the same size but the divisor -- old-fashioned arithmetic -- becomes smaller. Hence you get a bigger yield from the division.

Few stocks in the S&P 500 ($INX) had a bigger dividend than Supervalu going into Thursday's session, not because the dividend was outsized but because the stock had shrunk.

On Thursday we found out what happens when we see this process play out for companies that have battered balance sheets and declining fortunes. The dividend gets slashed, or in this case eliminated, despite all protestations to the contrary that anything like that could occur, including assurances given to me on CNBC last year by the CEO, of comfort with that dispensation of cash directly from the company to you, the shareholder.

Craig Herkert, the CEO, when asked about why the company eliminated the dividend, cited "holistic" reasons, whatever the heck that is. All I can say is it was a mighty bitter pill for shareholders, many of whom relied on that dividend as an important source of income. That $0.30 yearly, while not making up for the hideous two-thirds decline in the stock since 2008, did routinely draw in buyers with each reiteration of confidence that the CEO made.

There are some important lessons here. First, the supermarket space has gotten incredibly hard lately, a combination of dollar stores becoming more competitive in name-brand offerings, Target (TGT) and Wal-Mart (WMT) moving in aggressively, and Whole Foods (WFM) taking high-end consumers from mainstream shops such as Kroger (KR), Safeway (SWY) and Supervalu.

But second, and most important, is that sometimes outsized yields like Supervalu's are out-and-out red flags signaling their own reduction or elimination. Before blindly buying into management's assurances, before thinking "How can I miss with that yield protection?" do the homework. Supervalu was clearly in a long-term spiral down, something that told you to be more skeptical of the company's "confidence" in the dividend than you might otherwise be concerned about.

To me it's another clear-cut case of the need for not buy-and-hold, the preferred conventional wisdom of graybeards everywhere, but buy-and-homework. If you had done the homework, I believe you could bet that management couldn't fulfill its assurances, and you could have sidestepped Thursday’s hideous losses, the worst in the S&P 500 ($INX). 

Jim Cramer is a co-founder of TheStreet and contributes daily market commentary to the financial news network's sites. Follow his trades for Action Alerts PLUS, which Cramer co-manages as a charitable trust and has no positions in stocks mentioned.

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