A vote of non-confidence or no-confidence is a vote about whether or not a person is mentally or physically capable of holding a position of responsibility. It is not about whether or not a voter likes or agrees with a candidate.
For example:
Candidate A is someone a voter disagrees with. They have the option to vote for that person or abstain from voting. A vote of non-confidence would not be appropriate.
Candidate B is Cookie Monster, who has been added as a joke. While adorable, he cannot understand the role, or carry out its responsibilities as none of those responsibilities include eating cookies. Additionally, he is a puppet. A vote of non-confidence would be appropriate.