The General Data Protection Regulation (GDPR), Data Protection Authorities (DPAs) and the European Data Protection Board (EDPB) discuss purposes for data processing and the legal bases upon which data controllers can rely on: either "consent" or "legitimate in-terests". We study the purposes defined in IAB Europe's Transparency and Consent Framework (TCF) and their usage by advertisers. We analyze the purposes with regard to the legal requirements for defining them lawfully, and suggest that several of them might not be specific or explicit enough to be compliant. Arguably, a large portion thereof requires consent, even though the TCF allows advertisers to declare them under the legitimate interests basis. Finally, we measure the declaration of purposes by all advertisers registered in the TCF versions 1.1. and 2.0 and show that hundreds of them do not operate under a legal basis that could be considered compliant under the GDPR.