With regards to any auction, several variables can and do play a factor: the end time (morning, noon, evening, in the middle of the night for certain time zones), the day the auction ends, the platform (i.e. Sedo, eBay, Afternic ~ do bidders feel comfortable with the platform), media coverage or lack thereof, the accepted payment method (do bidders feel comfortable with the payment options, can they liquidate the funds in time etc), the seller's terms of sale, the seller's ability to contact the decision makers of possible end user companies, a bidder's knowledge of TM law or the lack thereof, etc.
As much as we would like to be able to forecast how things will turn out, if we are close to the end price, we are just lucky at best.
Earlier this year, I auctioned PaintballGuns(.)com on eBay and the bidding ended over 50k (reserve not met). A couple of months later, I sold it for $170k to an end user. Both Moniker and Sedo appraised the domain for under 40k AFTER my eBay auction had ended.
An appraisal is simply an educated guess.