Editor's note: A version of this post originally appeared on Richard Mahony's website.

Poor Bank of America. It scooped up mortgage-battered Countrywide Financial in 2008 for what looked like a bargain price, and it has been paying ever since.

Including last week's deal with the U.S. Justice Department, the acquisition of Countrywide has thus far cost B of A shareholders over $50 billion in regulatory settlements. That figure doesn't count the damage to the B of A brand, which was badly scarred by the misdeeds of Countrywide. B of A's ordeal serves as a reminder that blanketing the market with the buyer's brand isn't always the right approach.

In its press release last week on the regulatory settlements, B of A was quick to point out that other guys — Countrywide and Merrill Lynch — did most of the bad stuff. The media largely ignored that fact — an unsurprising development, considering that chief executive Brian Moynihan didn't do media interviews or hold an investor call clarifying that the bank inherited these problems rather than created them.

Moynihan's reluctance to dwell on Countrywide is understandable: the deal was a disaster for shareholders. But by staying silent, he reinforced the misperception that B of A was responsible for the worst excesses of the mortgage crisis. This confusion is rooted in a decision made years earlier to re-brand the Countrywide business with the B of A name.

Buying Countrywide was the handiwork of Moynihan's predecessor Ken Lewis. Ironically, under Lewis, Bank of America had been cautious about building up its mortgage business. As CEO, Lewis was often heard to say that he "liked the product but not the business" of home mortgages. But when Countrywide was weakened by the housing market's collapse in early 2008, Lewis pounced.

A few months after the purchase, B of A launched a mortgage lending push under a newly created brand, "Bank of America Home Loans." It proudly announced in a press release that the new brand would replace the Countrywide name.

And so, with a single stroke, the B of A brand adopted all of Countrywide's problems.

Those problems were well-known at the time, as Countrywide and its executives were subject to lawsuits and investigations by state and federal officials. Although these actions had yet to play out, B of A didn't hesitate to put its brand on the business. This turned out to be a colossal misjudgment: Countrywide's legal problems dragged on for years, scarring B of A's brand every step of the way.

So what could B of A have done differently?

For one thing, it could have retained the Countrywide name and re-launched it with a redesigned brand identity. Or it could have renamed its mortgage business entirely, if it judged the Countrywide name to be too damaged to salvage. (Think of GMAC re-branding as Ally Bank in 2010 after receiving a $17.2 billion government bailout.) Either way, this "new Countrywide" would have signaled a fresh start for the company and created some separation from the parent.

In truth, it would have been a tall order for B of A to truly distance itself from Countrywide. B of A was going to write the checks for any legal settlements regardless, and regulators, stung by criticism that they weren't tough enough on big banks, were going to keep B of A's name front and center in any enforcement actions. B of A may have also been operating under the assumption that a single brand would be more efficient and give it a better chance of cross-selling banking products to customers — a common enough strategy, though the evidence for such cross-selling is mixed at best.

There's a lesson to be learned from B of A's woes. In a world where regulators are likely to be aggressive and persistent, a troubled acquisition can stay toxic for a long time. In the future, banks will need to be even more careful about where they put their name.

Richard A. Mahony is founder of Mahony Partners LLC, a risk communications consultancy that has worked with many financial services firms.