Donna, I also use the interactive feature on the TV re: bill, but some cruise lines do not have this available.
I always double check the TV, my own list of receipts/date/amt spent, and printed out list which I receive from Guest Relations.
I have found a few mistakes: some things not posted, some things posted a few days after the fact, other things which were posted and I did not know about (an additional charge for additional entree on HAL and Carnival, an additional charge for wine (wrong price in the amount of being overcharged on Celebrity by $400), additional charge for a cookbook which I know I did not order, etc...As soon as I see these charges, I'm either on the phone calling G.R. or the department where it was so called charged and get it straightened out immediately. Heck, $400 is $400 I did not agree to and it's better in my pocket than the cruise lines.
I have too much to do when I'm home: picking up the kitties, unpacking, washing, ironing, catching up with the mail, etc. and that is one less thing I have to do so it gets done before we disembark and in person.