It's totally fine for it to be vague. I very much doubt we'll see any cases where the general public disagrees with a DPA ruling of LI applicability. As a business owner, it means you need to strongly justify it and consider if a "reasonable person" would consider your use of LI to be justified. If you have doubt, you should seek consent instead.

Do keep in mind, that growing your business by using PD for marketing purposes is explicitly excepted from LI.

Consent may not apply:

> Consent is presumed not to be freely given if... the performance of a contract, including the provision of a service, is dependent on the consent despite such consent not being necessary for such performance.