If a practice can be categorized as a misleading practice, it is not necessary to determine whether this practice is also contrary to the requirements of professional diligence.
"48.In the light of all the foregoing considerations, the answer to the question referred is that the Unfair Commercial Practices Directive must be interpreted as meaning that, if a commercial practice satisfies all the criteria set out in Article 6(1) of that directive for being categorised as a misleading practice in relation to the consumer, it is not necessary to determine whether such a practice is also contrary to the requirements of professional diligence as referred to in Article 5(2)(a) of the directive in order for it legitimately to be regarded as unfair and, therefore, prohibited in accordance with Article 5(1) of the directive."
IPPT20130919, CJEU, CHS v Team4 Travel
C‑435/11 - ECLI:EU:C:2013:574