First sign. The person criticizes you, but pretends to do it in good faith. For example, you have tried and prepared a table for a party. Man comes in and says, "everything is fine, but there is no my favorite salad. And the hot meal could have been better. I hope I helped with my advice."
That is, the person hides behind advice, but in fact reduces your self-esteem and credibility in the eyes of others. If the person desires evil, he will constantly spew such things. The purpose of such a person is to jab you. It is better in front of other people. It is safer and the effect is stronger.
Second sign. Such a person cannot rejoice in your victories and successes. For example, you tell that you have a new purchase, or a promotion, it doesn't matter. If the person wishes you well, he will sincerely congratulate you. And if the person does you evil, he will restrain his emotions.
He will try to show joy, but, as a rule, such people are bad actors. It is important to look at the face, not at the words. Mimicry will say a lot. It is the same with bad news. A person can smile for a moment and then feel sorry for you. But inside he will have joy.
The third sign. A person avoids one-to-one communication. Because, firstly, he is afraid that he will be found guilty of wishing harm. Secondly, he doesn't particularly like communicating with the person he wishes evil.
As a rule, this person speaks out about you exclusively in company. The larger the person, the more willingly the person speaks. Therefore, he will avoid seeing you one-on-one. That is my opinion.