As the originator of this post I was quite surprised at Galaxy Flyer's comment that boss don't care so he don't care. But I am very heartened to hear that other bosses and therefore other operators do care.
I certainly know my boss does care. I am paid to operate his aeroplane efficiently, safely and at reasonable cost. I go through all the receipts very carefully - at this stage I cannot do much about outrageous costs, but I go out of my way to ensure there are not charges slipped in for services we did not receive, or that there are no extra zeros "accidentally" added. I just hate corporate thievery - so sometimes its more about getting one back at the FBO than actually saving the money.
Some of the posts here about "doing something about it" have given me food for thought. In fact next time we go into the port in England where we were charged $16 US to throw a rubbish bag in the bin, I will write to the manager (who is a great guy) and tell him we won't be using his FBO due to charges such as this. Sure, the next FBO will probably charge the same, but then I will tell them that they have lost my business as well - they will get the message soon.