Does your sales organization ever complain that the leads you're generating aren't "qualified enough?"

First, ask those same salespeople what they think constitutes a "qualified lead." If the answer is "someone who's ready to buy," then you may need to reset expectations. A good lead generation program WILL uncover some prospects ready to buy, but that's not really the role of direct mail. A well-designed campaign seeks to a) identify people with a problem that your product can solve and b) get those people to respond.

If lead quality is a genuine issue, however, you may want to re-examine your offer. The goal should be to create an offer that generates a high level of interest but also attracts the right people. White papers are often ideal because they're perceived as having greater value than product brochures (hence higher response), but if positioned correctly, will also attract people who at minimum have the problem your product can help solve (see above).

Just because an offer is genuinely "information of value" and doesn't overtly sell your product, it still may be a poor offer. A book on using the Internet for example, may attract a high response, but what does it tell you about the prospect? Virtually nothing. In contrast, a white paper on "7 Steps to Building Powerful Java-Based Applications" will attract prospects who at minimum are looking for better ways to create applications and/or may be frustrated with their current solution.