It has been 25 years since McDonald’s first tested out its crab cake sandwich, and it seems to be an anniversary long forgotten—and for good reason. As was discussed by two Maryland-based radio hosts with much laughter recently, the flop had as much to do with where the culinary creation made its debut as how the sandwich tasted.

You see, McDonald’s decided to test out its “crab cake” sandwich along Maryland’s eastern shore, including two stores in Baltimore. Maryland, the crab cake mecca, where crab cake lovers gorge themselves on critters caught, steamed, and consumed locally. One might think that, because Maryland is a place where crab lovers live, a crab cake sandwich would be a perfect fit. On the other hand, one might think that, because Maryland is a place where crab lovers live, this as one of the worst possible places for the Golden Arches to introduce a crab cake sandwich. After all, this audience knows what crab cakes are really supposed to taste like.

Noted one radio personality, “I was born in Baltimore. They ONLY place I will eat a crab cake is in Baltimore!” And she didn’t mean the Baltimore McDonald’s.

Twenty five years later, nobody even remembers that McDonald’s had a crab cake. Yet, unbelievably, McDonald’s is at it again. They have introduced a crab cake in another coastal city, San Francisco. This time, the recipe was developed in conjunction with a celebrity chef. This is mystifying to me. Did McDonald’s really think the failure of its 1993 sandwich was the result of the taste? Sure, the sandwich probably didn’t taste all that good, but is tweaking the recipe going to fix the problem? Not if the problem is more fundamental, such as the fact that they were marketing it to the wrong audience.

Coastal foodies know crab, and regardless of the recipe, they don’t like their crab in a Styrofoam box.  It’s kind of like Little Caesar’s kicking off a new pizza crust in Italy. Because these audiences are in crab-loving areas, they are unlikely to be receptive to fast food crab cakes of any kind, whether the recipe was any good or not

What does this have to do with us? When doing demographic targeting, make sure your customers are not making overly simplistic, superficial connections that could work against them. Let’s take the example of one of the most popular target audiences right now: Millennials.

It’s popular now to market to “Millennials,” but while Millennials are often discussed as a homogenous group, they aren’t. Younger Millennials may still be in college, or just out of college, while older Millennials have been out in the workforce for awhile and are more likely to be married, have young children, and have more earning (and spending) power. They may all be “Millennials,” but how they spend their money, why they spend their money, and how much money spend will be very different. If you over simplify (“If Millennial, then this offer”), it could be like trying to sell fast food crab cakes in Baltimore.

As the MSP, your job is to ensure that your clients are not trying to launch a fast food fail. Consult with them to ensure that their “if-then” scenarios are realistic and tested, and that they truly have an understanding of who their audience is and how they tick. Only then help them using data to target their marketing in a way that makes sense.