Dividend Kings have excellent track records for dividend growth, and are often seen as some of the safest income investments to own. Two dividend growth stocks that may look tempting and that investors may want to take a closer look at today are AbbVie (ABBV 0.69%) and 3M (MMM -0.10%). They have been struggling this year and their yields are up over 4%. Here's a look at what's gotten investors bearish on these stocks -- and if they're good buys right now.

1. AbbVie

Healthcare company AbbVie pays a dividend yield of 4.1%, which is more than double the S&P 500 average of 1.7%. Including when it was part of Abbott Laboratories, the company has been increasing its dividend payments for 51 consecutive years. AbbVie also looks to be in a strong position to continue paying and increasing its dividend. That's because in each of the past two years, its free cash flow has totaled more than $20 billion -- double its annual dividend costs of $10 billion.

At face value, AbbVie looks like a solid dividend stock. But one of the reasons investors haven't been buying up the stock, and why it's down 10% year to date, is that it's facing some uncertainty in its top line. Top-selling drug Humira has begun to lose patent protection, and this year management expects sales to decline by 37% -- and that's on the low end of an initial estimate that projected sales could drop by as much as 55%.

Despite the drop in revenue, AbbVie still has growth catalysts for long-term investors to count on. Rinvoq and Skyrizi are two fast-growing immunology drugs that AbbVie expects could combine for higher peak annual sales than Humira. And last month the company announced positive results from a phase 3 trial from migraine medication Qulipta (atogepant), a potential blockbuster drug whose sales could top $1 billion.

AbbVie isn't at its 52-week low, but its share price has been sliding this year, and investors are turning bearish on the company. If you're willing to buy and hold the stock, AbbVie could make for a great income-generating investment to have in your portfolio for many years.

2. 3M

An even more impressive dividend growth streak comes from 3M. The conglomerate, which makes healthcare, industrial, and consumer goods products, has increased its dividend for 62 consecutive years. Its 62% payout ratio is modest, and this too is a stock that at first glance appears to be a safe option for dividend investors.

3M's business for the most part is stable, and it could make for a reliable long-term investment. Year to date, however, its share price has crashed more than 17%. The big risk facing the company today is that is financials are deteriorating and they could get worse. Gross profit margins, for example, have been falling over the past five years:

MMM Gross Profit Margin Chart

MMM Gross Profit Margin data by YCharts

Net sales of just over $8 billion for the period ended March 31 were down 9% year over year, but worsening margins resulted in the company's net income of $976 million falling more heavily, at a rate of 25%.

The bigger issue is what may lie ahead as the company is facing hundreds of thousands of lawsuits relating to its earplugs, which military personnel claim were ineffective and failed to protect them from loud noises. It has the potential to be a crippling legal battle for 3M. The problem is that it can be difficult to estimate, but given the number of plaintiffs it wouldn't be unreasonable to expect that the costs could be in the tens of billions -- at least.

As a result, 3M isn't the rock-solid investment it has been in years past. Its dividend can withstand worsening margins as its payout ratio remains manageable. But the looming legal cases present too much risk for this to be a stock worth taking a chance on right now as even its impressive dividend streak could be in jeopardy.

Although 3M's 6% dividend yield looks incredibly appealing, this is a stock that would only be suitable for contrarian investors who are comfortable taking on a lot of risk.