Answer: contaminants of communication in an interview may range from non verbal to verbal communication.
The gestures and expression that one makes may contaminate the interview
For example a non smiling and impolite potential candidates may give an idea that it will be hard to work with them .
Slouching on the couch whilst speaking to the interviewer may portray that someone may potentially be lazy or they don't take things to serious .
Chewing gum during the interview may bring that attitude of someone who is disrespectful.
The way someone is dressed up also
has an impression on the interviewer about the interviewee, which can be negative if one chooses to dress up inappropriately for that position that they applied for.
Verbal contaminations may be the way one responds , the langauge they use because the interview is a formal process if one doesn't stick to formal langauge it may give the idea that they don't take things professionally or they can not be trusted to communicate professionally.
Being over confident in ones own abilities may tend to portray them as arrogant individuals who may be hard to work with or manage.