Overspray is a big problem for marketers just as it is for people who paint houses with a spray gun (this is how most people paint stucco houses these days), getting paint on the windows costs paint and worst yet costs inconvenience to the home owner (or the painter) who either has to remove the paint or live with the ugliness of paint splatter on the glass.
The same concept applies in marketing. If a marketer buys an advertisement in a local newspaper for a nail salon, the natural overspray (at least in most cases) is the 50% of the readers who are men who are unlikely to ever use the services of the nail salon or ever buy from them. Even among the female population, there is significant overspray depending on the location where the actual nail salon is, the hours, whether or not the woman actually are in the market for a new nail salon.
So in an ideal world, marketers would love to target only the prospects who are perfect customers for them. Customers who are in the market for their product, in the right place, right time, right geography, right price range, with money, etc.
Overspray in marketing also has a cost. The cost is the attention and irritation that can build in the cunsumers that are over-sprayed. The biggest place where this is apparent is in email marketing. I try never to give out my email address if I can avoid it, simply because some people take an email address and then spam me with offers for products that I would never buy and have no interest in. In this case, I am the overspray. My inconvenience is having to look at it in my e-mail and delete it. In this case, overspray is easy for the marketer although it still has some cost to enter in the email address and it can have a cost in goodwill, because if a company is particularly aggressive at spamming me, I may get irritated and send them an e-mail or tell all of my friends about it. It can cost a company reputation in the community.
So we recognize the problem but I've never particularly liked problems unless there are solutions. The solution most publications use is publishing demographics on who their readership is. So a magazine, newspaper or television show will say that it's predominantly read or watched by an audience in a certain age and socioeconomic bracket. This method helps but is not perfect. Although 80% of their readers might be in the right demographic, there will still be overspray as mentioned earlier.
One of the best ways to target is to market to buyers who have proven a predilection to buying your product. For example, I have been doing some consulting work for a vitamin company. Doing emails or mailings to their previous customers makes total sense.
Another technique is targeting a customer who buys a similar product. For example, it's probable that someone who buys a fur is likely to buy jewelry. And of course in each case there is a price point, someone who buys $20 costume jewelry is in no way likely to buy a fur.
One mistake marketers make is believing that getting more people to see or hear their message is better than less people. In reality I would argue that you're better off to have more of the right people listening to your message and with more of the right people listening, you can make more of your sales.
For example I would rather send a newsletter to 500 people who have a 50% chance of buying from me (250 sales) than to 10,000 who have a 1% (100 sales) chance of buying from me.
Targeting can have the added benefit of reducing the overall cost of marketing even though targeting often increases the cost per contact. Buying a particularly targeted list will cost more per contact than a general flyer drop but because you can print and send less flyers, the overall campaign can be less expensive.
Split run testing is another way to determine how good an audience is for the message. Send the message to 2 or more different audiences and see which one has the best result.
Marketing is all about the numbers and analyzing results from the numbers and in many cases too much overspray reduces the value (money spent to business achieved) of a marketing campaign.
Jim Estill