This weekend, AdAge published two articles discussing the lengths to which advertisers are collecting and using data to target consumers for ads. One article details some of the techniques, and the other discusses the potential negative implications.

In short, marketers are increasingly taking data from offline sources and finding ways to apply this data to ad targeting across channels, including the internet.

Needless to say, these marketers are playing with fire. Privacy advocates are incensed that marketers could use data points like credit rating and historical purchasing records, and ‘privacy‘ and ‘consumer protection‘ are three words politicians around the world can count on when they need an excuse to push new regulations that appear consumer-friendly.

But in my opinion, the debate over the use of more advanced data mining by marketers is, in most cases, a red herring. That’s because behind the knee-jerk reactions to the fact that marketers are using personal data to target ads, there is an inconvenient truth: the effectiveness of this is often questionable. As we’ve seen online with behavioral targeting, for instance, doesn’t always produce results. One eMarketer study found that less than 13% of respondents found that more than 25% of the behaviorally-targeted ads they received were relevant. Which begs the question: despite all of the targeting techniques in use online today, how many of the last 10 ads that were served to you stood out as being relevant? Exactly.

Therein lies the rub. Marketers might know everything about you, from your age to your income to what you ate for dinner last night. But it’s not necessarily going to help them develop a cogent, compelling message. It’s not necessarily going to help them hit you with that message at the right time and place.

Don’t get me wrong: data mining can be a very valuable tool for marketers. But data mining, like everything else, needs to be done thoughtfully and with purpose. It’s about looking at the right data points, and applying them in the right places. In many cases, a lot of the data companies collect and analyze has far more relevance outside of the marketing realm than it does in it.

None of this, of course, means that marketers will think twice about whether or not aggressive data mining serves any practical purpose, or whether or not the analysis of all this data can actually be effectively turned into actionable insight. Marketers will continue to be on the lookout for bigger and better, even if bigger and better isn’t better.

But smart marketers aren’t interested in using all the tools that are at their disposal just because some are new and shiny. Smart marketers are interested in using the right tools to get the job done most efficiently and effectively, maximizing ROI in the process. Marketers who think that trying to figure out everything about consumers is the holy grail will be searching a long time for that ROI.