I'm not in a good mood. If you were a fan of Miami-based sporting teams over the weekend, you, too, would be feeling a bit bitter. How did the Florida Marlins lose on Sunday after scoring four runs in the 10th inning? Turning to the gridiron, can the Miami Dolphins or University of Miami Hurricanes play any sloppier?

You don't care. You shouldn't, really. This is a platform for investors. I just need to find a suitable topic that will let me vent my frustration. Now ... what can I pick apart that will turn my violent keyboard-pecking into something more constructive than destructive?

Oh, I know: mutual funds that specialize in socially responsible investing.

Seethe no evil
I guess it isn't politically correct to bash SRI. The perception is that funds that try to do the right thing by investing only in companies that meet their stringent parameters are the good guys. Buy SRI funds, the thinking goes, and you can sleep with a clear conscience.

Well, I don't see it that way. In theory, that would make me the bad guy. But let's get through this entire article before we begin the casting call for villains. I think I have some legitimate reasons for staying away from this group of funds, and it's not just a matter of playing devil's advocate.

I have nothing against buying what you believe in. In fact, I was the one who wrote the "God, Inc." article about religion-inspired investing last year. The problem here is that many mutual-fund investors don't know what they're buying when they're snapping up shares of "clean" funds. Let's go over the three problems that I see here.

1. Drawing the line in a sandstorm
Can we ever come to some form of consensus as to what constitutes a sin stock? Are alcohol stocks taboo even if some church ceremonies involve the consumption of wine? Defense contractors are a no-no in many SRI funds, but can the argument be made that they protect more than they aim to destroy? Gaming stocks are a common omission on the basis that they support an addictive ailment, but does that hold true if the casinos behind those stocks bankroll the financial well-being on Indian reservations?

These are rhetorical questions, of course. Yet if you are adamant about SRI, then you have a set response for each of those situations. I know it. But where do funds draw the line? The truth might shock you.

Pax World Balanced Fund is voting next week to help relax some of its selection criteria. Last year, the company unloaded its stake in Starbucks (NASDAQ:SBUX) after the java giant partnered with distiller Fortune Brands (NYSE:FO) on a Jim Bean whisky-and-coffee liqueur product. Could this product ever become a major contributor to Starbucks' bottom line? It doesn't matter.

Domini Social Equity Fund won't give Hasbro (NYSE:HAS) the time of day because its Monopoly brand is also licensed on slot machines. The social index seems to have no problem in buying into the computer and networking companies that create the data backbone of these gaming parlors or even the soft-drink maker that profits from its role in the mixed drinks being dispensed to fidgety gamblers. Let's not even get started on the discussion that Domini's PepsiCo (NYSE:PEP) can be linked to childhood obesity and caffeine addiction. I'm a fan of Pepsi; I'm just not trying to pass myself off as a saint.

2. The collection tray runneth over
Pax World Balanced Fund has $2 billion in assets yet sports an expense ratio of 0.96%. Domini's fund, despite being a screened index fund with little portfolio turnover (9% over the past year), has an annual expense ratio of 0.95%. That's about three times more than what Vanguard's more popular index funds hit up their shareowners for. And the cap on the Domini fund will actually inch up to 1.15% in two months, after a management change.

The sad thing is that those are actually some of the cheaper funds in this niche. The Calvert family of funds may even hit you up with a load charge. No, these aren't nonprofit charities, and they have every right to earn a living. It's just a point that needs to be raised before we hand these fund managers their halos.

3. Belittling the whittling
There is an inherent problem in narrowing down the pool of potential investments. As an investor, you may do just fine by trying to concentrate your efforts on sectors you know the best. There is an advantage there. The same can't be said for SRI when it dismisses hundreds -- if not thousands -- of names, yet it still has to cover the same broad sectors as if it were open for all purchases. That may explain why the socially screened index funds run by Calvert and Domini have underperformed the market over the past few years.

Yet there are exceptions. The Neuberger Berman Socially Responsible Fund that Shannon Zimmerman singled out to Champion Funds newsletter subscribers is actually ahead of the S&P 500 over the past three- and five-year periods. Shannon also recently recommended Ariel Fund, a company that plays the SRI game the right way by screening lightly. It may hold off on tobacco-rollers like Altria (NYSE:MO) or weaponry makers like Smith & Wesson (NASDAQ:SWHC), but it still gives itself enough flexibility to buy into most of the investing universe.

Summing up the sins
I was a Pax World investor in the early 1990s. I ultimately didn't redeem my shares, and it wasn't because of my disappointment with the fund's lackluster performance. Ironically, I had a political objection to some of the charitable causes being furthered by the Pax World Foundation in Cuba.

I didn't see that coming. I didn't think that a fund that promotes shareholder activism would find me turning the tables. I don't regret it, though, because it inspired me to formulate my own blacklist of unacceptable equity investments.

My version of SRI is pretty broad. The big thing that would keep me from buying a "sin" stock would be if I believed the questionable part of the venture would prove detrimental to the company's future as a going concern. I wouldn't have dumped Starbucks. I wouldn't have dissed Hasbro. As an individual investor, I have the right to make that call.

You know, like making the call that I should have made and avoided watching my local teams fall apart over the weekend.

Like funds of all persuasions? Then check out our Champion Funds newsletter service, which picks apart mutual-fund winners while educating you on the right way to buy funds.

Starbucks and Hasbro are Motley Fool Stock Advisor recommendations.

Longtime Fool contributor Rick Munarriz believes that mutual funds are an important part of any stock portfolio. He does not own shares in any of the companies mentioned in this story. Rick is also part of the Rule Breakers newsletter research team, seeking out tomorrow's ultimate growth stocks a day early. The Fool has a disclosure policy.