B2B data decays at a rate of over 70% per year, according to the infgraphic, which means you could be referencing someone's old position or company when you contact that lead.
Furthermore, bad data means your lead scoring could be wrong, which makes it easy to lose sales opportunities. And, the infographic points out, many marketing automation price strcutures are based on the size of your database, so holding on to outdated data can cost you in fees as well.
The infographic closes with a reminder of the 1-10-100 rule: It costs $1 to verify a record as it comes in, $10 to clean it later, and $100 to do nothing. Even if those figures aren't exact, they paint a clear picture of how dirty data can be costing your brand.