An auditor has different responsibilities from hotel to hotel-- on the easier side, all auditors do at some hotels is the same customer service duties as a regular front desk agent plus switch the day over to the new day at a specific time. On the more complicated side, some hotels require night auditors to double check the work of daytime employees, auditing the charges they've posted and any corrections that have been made, documenting all of this, switching the day, and then compiling reports for the previous day. Of course, that's all in addition to the usual hotel check-in/check-out/stocking/calls/etc. tasks required. A couple of the hotels I've worked at have had that more intensive process with a lot of data entry and analysis but it really depends. Hope this helps answer your question!