It's very important. You need to know as much as you can. By that I mean, it's important for auction sellers and bidders alike to protect their interest by learning about an auctioneer's style, habits, reputation, and, most important, character. You need to know what kind of person the auctioneer is. You need to know what kind of auction he's going to conduct and how he's going to conduct it.
Many people are just too trusting, especially when it comes to important financial decisions.
That appeared to be the cardinal mistake made by the letter writer mentioned above. It seemed she knew little or nothing about the auctioneer before she consigned valuable property to him and then ended up with a surprising and disappointing result. If she had exercised reasonable caution and prudence, she may have avoided the situation that damaged her. She didn't and got burned. What a shame.