Since 2004, Yelp (ticker: YELP) has mounted a lively platform to air gripes, sing praises and assign ratings to any kind of consumer business you can think of, from airbrushed nails to zoos.

That’s resulted in more than 90 million user reviews as of the third quarter of 2015 — but how that translates into millions in steady revenue is another story. And speaking of ratings: Who gets to rate Yelp as an investment?

Not even Yelp’s much-promoted mobile app will give you that kind of information (let alone the phone number for Chinese take-out from the company cafeteria). But investment experts raise poignant concerns about the San Francisco-based company.

Mixed reviews for YELP stock. If you made a long play for Yelp and bought it in March 2012 during its initial public offering, you’re still waiting for the company to take flight — or fix its broken wings. Since it launched, Yelp stock is down more than 20 percent. By comparison, Facebook (FB) stock has nearly tripled over the same period.

Even at IPO time, market observers cautioned that Yelp had just suffered two consecutive years of net losses. But at the time, companies such as LinkedIn (LNKD) and Groupon (GRPN) created a social media IPO feeding frenzy. Since then, it’s been a mixed affair: LinkedIn’s stock price has doubled — before Thursday’s disastrous earnings report that knocked more than 25 percent off LNKD stock’s price — while Groupon’s drop of nearly 90 percent has been enough to make a sinking battleship jealous.

Somewhere in the murky middle lies Yelp, a company that still inspires visions of a comeback for those who remember its stock run higher by 300 percent between March 2012 and March 2014. But all those gains have since been erased, and then some. And when Yelp releases its latest quarterly earnings report on Monday, there’s no guarantee it will boost investor confidence.

Earnings history. Yelp investors got a shot in the arm in the third quarter of 2015 as the company posted net revenue of $143.6 million, beating Wall Street expectations of $141.42 million. Yelp also grew revenue 40 percent from the previous year, but to get there, it also discounted non-cash costs such as share-based compensation for its employees.

So on a GAAP basis — that is, using generally accepted accounting practices — Yelp lost $8.1 million, or 11 cents per share.

“Its ticker symbol is YELP, but from the investor’s standpoint, the ticker symbol just as well could be YUCK,” says Robert R. Johnson, president and CEO of The American College of Financial Services in Bryn Mawr, Pennsylvania. “It has fallen by well over 50 percent this past year. The stock sells at a rich price-to-earnings ratio of 67 times earnings and has had difficulty in monetizing its business model.”

That could well mark Yelp’s latest case of hard luck. Back in 2009, Google — now known as Alphabet (GOOG) — tried to acquire Yelp for a reported $500 million. But that deal blew up and led to bitter feuding between the companies, along with competition for the same audience. From an investment point of view, you can guess who’s losing the battle. (Hint: It rhymes with “help.”)

“Even Yelp insiders are leaving the table, as COO Geoffrey L. Donaker sold 6,000 shares in January, according to the Securities and Exchange Commission,” says Nick Martell, co-founder of the MarketSnacks, a daily financial newsletter based in New York.

But good news did come, briefly, in November: Yelp stock surged more than 25 percent that month when IAC/InterActiveCorp. (IACI) made an offer to buy out review site Angie’s List (ANGI).

The pressure’s on Yelp. Meanwhile, Yelp is making a serious play to pump up its earnings. “The company is aggressively spending on their sales force in an effort to gain first-mover advantage with local businesses looking to improve their online visibility,” says Brian Hellmer, director of the Hawk Center for Applied Security Analysis at the Wisconsin School of Business.

But that has hurt recent earnings results versus prior expectations, Hellmer says. “It’s not surprising that the stock has been under pressure, given that they’ve had to ramp up spending to maintain growth rates and aggressively use stock-based compensation for employees as well.”

“Yelp is still a fairly young company, but its historical earnings record reveals a struggle to be profitable,” says Angelo DeCandia, professor of business and accounting at Touro College in New York. “Annualized quarterly earnings have been a roller coaster over the past several periods, buttressed only by a strong finish at the end of 2014.”

Some bad press. Then there is the issue of bad press, which Yelp seems to attract with alarming precision. While that may not directly correlate to driving company revenue, it certainly doesn’t aid the cause — let alone bolster investor confidence.

A soon-to-be-released documentary, “Billion Dollar Bully,” accuses Yelp of highlighting negative reviews if businesses fail to cough up cash for ads. “And if reviews are from disgruntled customers, it can tear down that business even if the reviews are not accurate,” says Leigh Held, a journalist who wrote a 2014 article about Yelp in Entrepreneur magazine.

To that end, portals such as the “Yelp Sucks” website now watch the company’s every move. “Negative comments have dropped off a bit, down 36 percent over this time last year,” says website founder Adryenn Ashley. “But does that mean the company is finally taking a serious look at the issues business owners have been bringing up over the years? Or are they finding outside help from reputation experts? The answer is both.”

What should investors expect from Yelp earnings? As for whether smart investors should expect a burst of sunshine should Yelp once again beat Wall Street, or gathering thunderheads in the form of more losses on the GAAP side, the answer, once again, is both.

“The numbers tell us is that Yelp is a company good at generating revenue, but so far unable to convert that into a meaningful earnings stream,” DeCandia says. “That’s a signal that successfully investing in this stock will require patience and a longer timeframe than Wall Street’s quarterly earnings cycle.”

Adds Johnson: “The bottom line is that Yelp may be a good source to figure out where to dine. But buying the stock may give you heartburn.”

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Earnings Preview: What to Expect From Yelp Stock originally appeared on usnews.com