So, what's the real story with Comerica (NYSE:CMA)? Is this an undervalued bank with potentially valuable footholds in California, Texas, Arizona, and Florida? Or is it a company in serious trouble, with weak earnings, ample competition, and eroding share? Unfortunately, the answer is probably "both," which makes an investor's job a bit more challenging.

This wasn't a good quarter. Revenue was up 4%, as net interest income rose about 4% and non-interest income rose close to 3%. I realize that this is a tough environment for banks, but if you can't grow your top line at the pace of the country's GDP, you're already in trouble. Non-interest expenses continued to climb faster than revenue, and the company saw net income drop 8% from the year-ago level.

At least there's still some balance-sheet growth. Average loan balances rose more than 10%, and deposits were up 5%. But I'm discouraged at the continuing decline in non-interest-bearing deposits, which have been an advantage and source of strength for Comerica and others like UnionBanCal (NYSE:UB), ZionsBancorporation (NASDAQ:ZION), and Commerce Bancorp (NYSE:CBH). After all, if you pay basically nothing for money, it's easy to make a positive return on it.

The company is considering selling its interest in Munder Capital, which could raise a substantial chunk of money, considering what Merrill Lynch (NYSE:MER) recently paid for BlackRock. But that doesn't solve the problem of tough economic times in Michigan, due to General Motors' (NYSE:GM) and Ford's (NYSE:F) troubles, nor the cooling housing market in California. It'll also be interesting to see how management spends the proceeds if it does complete a sale -- will it look to buy back some of its market share in Texas and California through another deal, or focus on de novo expansion?

Stocks like Comerica are partly why I'm graying before my time. Even with exceptionally modest growth estimates, the shares look undervalued, but I suppose it's fair to ask whether they can accomplish even exceptionally modest growth. Ultimately, I think this may be a "use it or lose it" proposition. If Comerica doesn't do better, it'll get bought, which at least offers a potential floor for investors.

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Fool contributor Stephen Simpson has no financial interest in any stocks mentioned (that means he's neither long nor short the shares).