General Motors' rental car service, Maven, in action. Image source: General Motors.

Large dividend payments are appealing -- the promise of a steady stream of cash infusions can entice virtually any portfolio manager. For that reason, investors are rarely given the opportunity to scoop up dividend stocks at a discount.

But from time to time, dividend stocks do go on sale. Here are three companies that boast impressive dividend yields and trade at bargain valuations. There are reasons to be skeptical of all three businesses, but each company is generating strong cash flow -- enough to pay yield-seeking investors for the foreseeable future.

General Motors is yielding more than 5% and trading at just 4.39 times trailing earnings

Auto giant General Motors (NYSE:GM) is one of the cheapest large-cap companies currently trading on the New York Stock Exchange. Rivals Ford and Fiat Chrysler are not expensive stocks by any means, but their valuations are loftier than GM's, whose single-digit price-to-earnings ratio currently sits below 5. At current levels, investors willing to hold GM shares will be paid 5.23% of their investment each year.

Fears about GM's long-term business prospects abound. The emergence of self-driving car technology, ridesharing apps, and electric cars stand to disrupt the automotive industry in a way that's not been seen in many decades. But GM isn't sitting still: Earlier this year, it invested $500 million in Uber rival Lyft and acquired self-driving automotive start-up Cruise Automation for more than $1 billion. It launched car-sharing service Maven in January. Its Chevy Bolt isn't as impressive as the Model 3 but will be available much sooner.

GM generated $152.4 billion of revenue in 2015. Analysts expect the company's revenue to rise to $155.48 billion in 2016 and $157.44 billion in 2017. Unless GM's business takes a dramatic downturn, the company should be able to continue paying investors. Management believes it will generate nearly $6 billion in free cash flow this year.

Western Digital is digesting a controversial acquisition

Western Digital (NASDAQ:WDC) shares have fallen more than 50% over the last 12 months. Much of that loss comes in the wake of the company's decision to acquire flash storage specialist SanDisk and the dissolution of its agreement with Unisplendour, a Chinese company that had planned to purchase 15% of Western Digital's stock. More generally, fears about the ongoing decline of the traditional PC have pressured Western Digital's business, as the company derives much of its revenue from the sale of hard drives.

Western Digital had to take on additional debt to finance its acquisition of SanDisk. Last month, it reduced its earnings outlook based partially on interest payments associated with that debt. But Western Digital is now a diversified storage company, with almost two-thirds of its revenue coming from non-PC sources. Within the PC space, hard drives face increasing pressure from flash-based solid state drives. With the SanDisk merger now complete, Western Digital has become a major solid state drive provider.

At current levels, Western Digital is trading with a trailing price-to-earnings ratio near 13 and yielding 4.27%. Its payout ratio has risen in recent quarters but is a manageable 56%.

Verizon is far less expensive than its rivals

With more subscribers than its major rivals, Verizon (NYSE:VZ) is the nation's largest wireless carrier. It also has the least expensive stock, trading with a trailing price-to-earnings ratio of less than 12. At the same time, Verizon boasts an impressive dividend -- at current levels, it's yielding 4.29%.

Competition in the wireless industry has heated up in recent years and remains intense. Verizon has had to alter its plans and the ways in which it offers subscribers smartphones, but its business has remained resolute. Last quarter, retail postpaid churn fell 7 basis points, down to just 0.96%. Verizon added 284,000 new smartphones last quarter and more than 500,000 tablets. Its wireline business also remained robust, adding 98,000 new FiOS customers last quarter. Verizon appears to be the early leader in next-generation wireless technology and plans to roll out 5G next year. Eventually, 5G-enabled smartphones could emerge, but at least initially, 5G connections will be aimed at providing in-home broadband. That could open up Verizon's business to new markets.

Verizon generated $4 billion in free cash flow last quarter, and its payout ratio is only 48.3%. It should be able to continue paying shareholders long into the future.

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.