It's the best of intentions that leads to a situation where smart media planners and ambitious marketers use technology and tactics that end up casting their lines beyond the edge of the fishing hole.

Sometimes it happens that at the end of extensive market research, an advertiser ends up with more identifiers for its target market than it knows what to do with or are necessary.

Women 25-54 with kids ages 6-17 in the household, who drink three-plus cups of coffee a day, might be how research has described the prospective target for a new line of premium instant coffee. But feed all of those filters into a targeting machine, add in a few extra filters of "behaviors" based on content engagement, and you end up with such a small number of audience prospects that they never end up having a chance to encounter your message.

Demographic filtering in concert with behavioral segments can leave you with an audience too small to actually find your message.

Another way over-targeting happens is when too many behavioral segments are put together with one another.

People viewing automotive content, insurance information and real estate websites might be people shopping for a new car, or they might be moving. Cross-tab all of these activities together and it is hard to know what kind of audience you might be reaching and what frame of mind they might be in. An advertiser might use all the above criteria to target people shopping for new cars, but it could just be that the person is a gear-head looking to insure his fiancée's engagement ring and looking at a picture of a house his friend wants to buy.