As for me, the way person replies on the other end of the phone, or how you are emailed back. I do not mean only corporate politeness, standart speech scripts and smiliness, but a feeling and readiness that someone from the company can devote a part of her time to answer your questions. And acts like this.
Two examples: I called one company regarding the position they posted on the jobsite. I was frustrated with the answer that they do not disclose any info on the position via phone. I still do not get a point. Another example (in second company) made me happy - the HR lady spent around 15 mins talking to me. I got a long-lasting impression. Why not spend "n" mins and spread that all candidates are welcomed and respected ?
I am sure it is better to leave an impression than frustration. It is DNA of Marketing in your organasation. Inspire staff with the importance of it.
Teach the frontline people be the marketers !