The employer looks for an optimistic and positive attitude. The employer looks for optimistic statements and positive reactions to his questions. Pessimism and negativism never win a job offer for anyone. The idea in interviewing is to elaborate on those things that you can discuss optimistically. It is not necessary to fake it.
Nothing is more obvious than phony or superficial enthusiasm.
However, if you are optimistic and positive about any facet of the position, don't fail to show it. The employer looks for an interest in the company and the position. The employer looks for someone who has a high opinion of the company and the position. The employer looks for indications of longevity of service. No employer wants to hire someone who will leave the company after a few months.