Criticism, or feedback could be viewed as negative for several reasons. The first may be the history between the two people involved. If they have had previous interactions that can be construed as negative, no mater what the intent was, suggestions could be interpreted as negative. Another factor could be how the person is presenting it. Tone of voice, body language, timing, location, and content of feedback would be deciding factors in interpreting how the message is received. A last factor to consider is the person receiving the message. If that person lacks confidence in themselves, the message most likely be construed as negative, no matter what the intent was meant to be.
If you are on the presenting end of this type of interaction, and you are offering feedback that is being interpreted as negative, I would suggest opening up a dialogue with that person. If you discuss this an issue, you can at least be opening the door to constructive dialogue. If the person receiving the feedback knows your motives behind the critique, it could allow future interactions to be more positive.
The person receiving the feedback could also help the situation by opening up a discussion about this issue. The person presenting the information may not be aware they are presenting it in a negative light. Help them understand why(be specific) their message is interpreted in a negatively. This could be helpful only if the person presenting the feedback is intending the feedback to be constructive. If the person is intending it to be negative, the person receiving it may need to avoid that person, set limits with him/her, or develop their own mental filter when around this person.