Zhao Yi gossiped about Liu Chengjie's confession and then thought about it carefully. He felt that the failure was quite normal, following the regular pattern, as 'licking' someone's boots generally wouldn't succeed. It made logical sense.
It's not because of the act of 'licking,' but rather an issue of perspective.
For example, a super good-looking wealthy second-generation wouldn't 'lick' an ordinary person because the former inherently feels superior and subconsciously thinks the latter is not good enough for them.
Only those in a weaker position would resort to 'licking' behavior in order to obtain their dream partner.
From the perspective of those being 'licked,' they also hope to pursue someone they like who's better than themselves, rather than turning around and accepting someone they don't like who is somewhat inferior.
The act of 'licking' itself isn't wrong. If used on the right person, it wouldn't be considered 'licking' but would become sweet love instead.