There are close to 20,000 publicly traded stocks in the United States. Only about 4,000 of those are actively traded on a major exchange such as the NYSE or Nasdaq. Even then, most of those are unworthy of owning a spot in your portfolio.

Sometimes the decision to not buy a stock depends on the type of portfolio you're building. Sometimes it requires looking at a company's market position, evaluating future risks, and deciding you'd be better off parking your hard-earned money elsewhere. That doesn't necessarily make it personal between you and the stock you're turning down. It just makes it right for you, personally.

With that in mind, I have clear reasons for never planning to buy Flotek Industries (NYSE:FTK), CVR Partners LP (NYSE:UAN), and Chemours Co. (NYSE:CC).

A businessman staring at a wall in front of him with many white arrows pointing to his left, and one large yellow arrow pointing to his right.

Image source: Getty Images.

Orange ya glad you didn't buy this one?

It sounds a bit ridiculous, but the largest risk to oil and gas drilling products specialist Flotek Industries is oranges. Yes, the citrus fruit. Yes, really.

Let's connect the dots. Following a devastating trio of Atlantic hurricanes, the company issued a press release in late September to set expectations for performance in the third quarter of 2017. It noted that client- and vendor-related business disruptions would result in quarterly revenue that was $5 million lower than originally expected and incremental cost increases of less than $1 million. 

One of single largest reasons for adjusting expectations lower is the devastating loss of citrus crops in Florida, estimated at an astounding 40% to 50% of the total crop. Why is that bad news for Flotek Industries? The company's products for energy, consumer, and industrial applications are all created from citrus oils -- and the main sources of citrus oils are orange peels.

The news was just the latest in a string of unfortunate developments that have pushed the stock lower in the past year.

FTK Chart

FTK data by YCharts

But it would be unwise for investors to dismiss the loss of half of Florida's orange crop as a short-term concern. That's because long before hurricanes wreaked havoc this season, growers have been contending with a far more terrifying threat: citrus greening disease. This ailment has sapped orange yields for years now, and since the industry has so far resisted calls to genetically engineer citrus crops resistant to it, there's only one way this ends. (Hint: I hope you don't like orange juice.)

Flotek Industries faces a similar existential threat to its business. Hurricane Irma took a long-term trend that was already pressuring the company and poured gasoline on it. Fewer oranges in the short term will crank up selling prices and therefore greatly increase input costs for the chemical products company for the next few quarters. But even if Florida's crop recovers, growers will still be fighting a losing battle against citrus greening disease.

Unfortunately, oranges, not the growth of oil and gas drilling, will determine this stock's future. As far as I can tell, it doesn't have one.

Nitrogen fertilizer may never recover

CVR Partners LP is a master limited partnership designed to pass on nearly all of its profits to shareholders each quarter. There's just one problem: It hasn't been profitable in over one year. While that has become a thorn in the side of CVR Energy -- a major owner of the nitrogen fertilizer manufacturer -- it has really stung individual shareholders.

Those holding out hope that things will get better for the nitrogen fertilizer market after a long down cycle may be disappointed. Of the three major agricultural nutrients, nitrogen has been the worst performer. In fact, it's the only one continuing to set new lows. It appears things will get worse before they get better -- and actually, they may never get better. 

UAN Chart

UAN data by YCharts

That's because supply continues to come online. It's a surprising antidote for the market's illness of oversupply, but some producers are making ends meet by selling higher volumes. Others are planning major new production facilities closer to America's Corn Belt to offset the pricing disadvantage. That hints that CVR Partners LP's woes could continue for the foreseeable future.

Although the company's operating margin has trended upward in the past year, it's far from being able to deliver the massive quarterly distributions that it was formed to dish out in the first place. Worse, the market's supply imbalance may not be the only concern for nitrogen fertilizer producers.

It's been flying under the radar for the most part, but one of the hottest areas in ag biotech for start-ups and established multinationals alike is engineering the ag microbiome. In English, companies are learning how to enhance the population of soil bacteria and other microbes that live on and around plant roots. The goal is to improve yield, protect against disease, and, oh yeah, potentially allow plants to get all their nitrogen needs from the environment.

It may not get much attention today, but the technology is much closer to reality -- and going mainstream -- than most people think. Within 10 years' time, the $80 billion nitrogen fertilizer industry could be on its way out. I wouldn't want to be owning CVR Partners LP anytime between now and then.

Polluters need not apply

Chemours took a little while to find its groove after being spun out of DuPont, but recent gains have probably laid any concerns from investors to rest. The specialty chemical stock is up an incredible 231% in the past year alone.

There are two primary drivers for the awesome gains. First, the company reached a settlement in a class action lawsuit regarding the dumping of a toxic processing aid that was formerly used during the manufacturing of its fluoroproducts. The removal of uncertainty started an epic run-up. A long-awaited recovery in selling prices for titanium dioxide products -- the second driver -- added fuel to the fire. That should be hardly surprising, considering Chemours is the leading global producer of titanium dioxide.

CC Chart

CC data by YCharts

Yet I know I'll never buy Chemours no matter how appetizing its future growth potential becomes. Why not? I don't think the legal headaches for its fluoroproducts dumping activities are over. Worse, the processing aid that replaces the chemical at the heart of the recently settled class action lawsuit is just as toxic as its predecessor -- and the company was dumping it as recently as several months ago.

Even if Chemours never faces another day in court or is threatened with major fines, I don't want to own it for the simple reason that it knowingly put profits over public health. The U.S. Environmental Protection Agency raised concerns that the latest chemical is incredibly toxic to birds, fish, and humans -- and the company went ahead and tossed it into waterways anyway. My wealth-building activities require socially responsible investing. Chemours doesn't come close to clearing the bar.

What does it mean for investors?

The simple fact of investing is that most stocks aren't for your portfolio. Everyone has unique experiences that shape how they view the world. My closeness to next-generation biotech provides me a unique perspective from which to disregard what others may see as investing opportunities in Flotek Industries, CVR Partners LP, and Chemours. Perhaps it provides an additional argument for other investors to consider.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.