Clean Rooms, Myths and Realities

Many clean rooms promote privacy by default, but not all are created equal. Using a data clean room does not, in itself, ensure GDPR compliance. Every processing activity carried out inside the environment still has to meet GDPR in full, including lawfulness, purpose limitation, data minimisation, and accountability. That needs assessing case by case, so the right legal bases, safeguards, and data protection measures are actually in place.

Clean rooms built privacy by default often carry hardcoded protections that prevent breaches and make compliance easier to reach. Privacy-by-design platforms tend to let users tailor privacy requirements, which introduces variability between implementations while opening up a broader set of marketing use cases.

A common assumption is that a clean room only works if you use the provider's own identity graph. That thinking creates lock-in and limits interoperability. An ID graph is primarily useful for cross-publisher or retailer attribution and frequency capping. It is not a requirement for every clean room, and no provider offers a universal, standardised ID graph, not least because there is no common ID system across media owners and markets.

Integrating clean rooms across multiple channels usually means connecting data through data lakes, or through identifiers held in cloud providers or CDP platforms. Because data sharing varies, particularly between platforms like Meta and Google, the approach and the capabilities differ significantly from one clean room to the next. Not all of them carry the same network of publishers and DSPs.

Some clean rooms are SQL or Python based and do call for data science expertise. Others are no-code or low-code, built so that a marketer can handle the simpler tasks without specialist help. Where that is the case, the end user is the marketer rather than an engineer. No-code DCR interfaces are often built on the cloud environment of a different provider.

The market tends to prefer deterministic data, yet clean rooms can also work probabilistically. Knowing which one you are dealing with, and what it lets you do, matters more than assuming everything is deterministic by default.