This little video, created by longtime assessor, Mr. Greg Gogates, provides a good example of some of the absolute worst reasons to become an assessor. See http://www.youtube.com/watch?v=zcYCDswjIEM&feature=youtu.be. Good assessors will base their words and their actions only on fact verifiable by evidence. Good assesors do not have opinions. And good assessors (while they may have opinions because they can be passionate about their science) should not have such high opinions of themselves, and their own opinions.
On the other hand, enjoy another short video being used by the Standards Council of Canada, an ILAC-Signatory accreditation body to recruit assessors. It shows the best reasons why we should want to become an assessor. See the video here.