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Citron’s Andrew Left says, ‘I’ve been more right than wrong.’ PHOTO: MICHAL CZERWONKA FOR THE WALL STREET JOURNAL

LOS ANGELES—Even in the bombastic world of short selling, Andrew Left stands out.

Mr. Left, the man who this week likened Valeant Pharmaceuticals International Inc. to Enron Corp., is among a small group of investors who publish free reports on firms they claim are overvalued or are engaged in fraud. They profit by making trades known as “shorts,” betting the shares will fall.

Unlike many of his rivals, Mr. Left issues reports laced with profanity, vivid anatomical descriptions and taunts directed at corporate executives. He ended a 2014 report with a parting note to his target’s CEO: “Your first reaction will be to want to sue me. I hope you do!” He said he has been sued but has never lost a case.

“I stand by my research,” Mr. Left said in an interview. “Fortunately for me, I’ve been more right than wrong.”

A report issued Wednesday by Mr. Left’s Citron Research accused Valeant of creating fraudulent invoices through a network of pharmacies it controls. The report compared Valeant to Enron, the energy-trading firm that collapsed in a 2001 accounting scandal.

Shares of Valeant, a Quebec-based drug firm whose shares were up 1,000% over five years at its recent peak, are down 27% since. Valeant issued a statement Wednesday calling the report “misleading” and “an attempt to manipulate the market.” The company said it plans to hold a conference call at 8 a.m. EDT on Monday to address recent criticism of its business practices.

“Sometimes you have a great story and the biggest challenge is, ‘How do I get people to read it?’ ” Mr. Left said in an interview in March 2014 at his home office in Beverly Hills, Calif. “Wall Street research is painfully boring. I enjoy being entertaining.”

The 45-year-old investor lives in a mansion in a gated community with an infinity pool overlooking Los Angeles, and Bentley and Mercedes cars sitting in the driveway. Slash, the former lead guitarist of rock band Guns N’ Roses, lives across the street.

Mr. Left, who invests only his own money, said he has made profits every year since he started short selling 14 years ago. A Wall Street Journal analysis of 111 Citron short-sale reports published from 2001 to 2014 shows an average share-price decline of 42% in the year after a Citron report was released. Of those shares, 90 were lower one year later while 21 gained, according to data from S&P Capital IQ.

“He’s the shock jock of short sellers with a fantastic record,” said John Hempton, a short seller and investor at Bronte Capital in Australia who has also published reports questioning Valeant’s business practices and accounting.

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His big-game record is mixed. He made a short call on Tesla MotorsInc. in 2013, saying the company’s electric car might be a fad and that valuations were euphoric. Sales have increased since, and the stock price has risen about 30%. A rare bullish call on flooring manufacturer Lumber Liquidators Holdings Inc. in March soured as the stock has dropped 50% since.

Some bets paid off but not until after sharp share-price increases that could have tested investors’ endurance.

In early 2013, Mr. Left set his sights on the stock of 3-D printing company 3D Systems Corp., which was trading at about $40. He argued that enthusiasm around 3-D printing was a bubble ready to pop, citing the use of 3-D printers to make sex toys as an example. 3D System now trades at about $12, but the shares rose throughout much of 2013, briefly exceeding $90 a share.

Others initially worked but would have burned investors who held on. In 2012, he set his sights on Questcor Pharmaceuticals, which manufactures an immune-system-disorder drug called Athcar. He hired a laboratory to analyze the medicine and said his tests showed different ingredients than Questcor advertised.

The stock initially lost two-thirds of its value, then rebounded when the company was purchased for $5.6 billion last year by MallinckrodtPLC.

Mr. Left runs Citron out of a plush home office full of memorabilia from Lehman Brothers Holdings Inc. and Bernard Madoff Investment Securities LLC. The upholstered chairs in his children’s bedrooms were purchased at an auction of office furniture from Enron. He also owns a print of the rap lyrics “Thinkin’ of a master plan,” from Eric B. & Rakim.

A blur of constant motion who usually wears jeans and an untucked button-down shirt, Mr. Left switches between multiple computers while fielding phone calls and texts from friends, his website’s editor, his lawyer and his wife.

He said he likes being far from Wall Street, where he can spend much of his time golfing and with his family. “Nobody cares about what I do here,” he said. “My own kids don’t know what it is I do.”

Mr. Left grew up in a middle-class Miami suburb and said he developed a taste for argument on his high school debate team. He first brushed with financial markets at 23, when he briefly took a job at a “boiler-room” brokerage aggressively selling risky commodity futures contracts to mom-and-pop investors.

The National Futures Association sanctioned the firm and gave Mr. Left a three-year ban for making false statements to sell commodity futures contracts. He credits the experience for launching him into short selling of stocks he identified as boiler-room scams.

He started out investing with money borrowed from a friend in 1995, tracking companies with suspect financial disclosures he recognized as boiler-room legerdemain or led by management teams involved in previous stock scams.

Mr. Left started writing scathing reports on a self-published blog called stocklemon.com in 2001. As his reputation grew, he developed a network of short sellers who feed him ideas.

He said he lost much of his wealth in a divorce in 2007 and decided to reboot, rebranding his website Citron Research, after the word for lemon in French. That year he focused on one bet against a construction company called Home Solutions of America that he believed was fabricating contracts tied to reconstruction efforts after Hurricane Katrina.

He wrote more than 10 reports on Homes Solutions and said he bet all his personal wealth against the company, which was valued at $390 million. The firm later collapsed, and Home Solutions CEO Frank Fradella pleaded guilty to securities fraud last year.

In recent years, Mr. Left said he has gone “elephant hunting,” targeting the pharmaceuticals industry, which he said is opaque and rife with abuses. When asked in a phone interview how he planned to respond to Valeant’s rebuttal, Mr. Left said, “It’s still a scam.” He hung up, then went to pick up his children from school.

—Austen Hufford and Andrea Fuller contributed to this article.

Write to Matt Wirz at matthieu.wirz@wsj.com