Influencer’s own opinion? No disclosure required
Fortunately, it is now clear: when an influencer is being very positive about a product, but the producer of the product has nothing to do with that influencer (the producer did not pay for the positive post,neither is the product sampled), such a positive post falls under the freedom of speech while the strict rules on advertising do not apply. The Advertising Code for Social Media is not applicable. In cases like this, there is no need to mention something like #adv.
Follow this link for the annotation that Ebba Hoogenraad wrote, recently published in IER 2019, no. 1.
Ebba Hoogenraad