When was the last time you looked at your contracts with your venue or your caterer carefully? Did you ask about every single charge on the bill? Did you read the fine print? I of course read the fine print over and over again. Even if I have used the location or the caterer before, I make sure to reread just in case.
What I've been noticing is an additional 20% fee added to a few venues or caterer's final bill. Now there are times I totally understand this charge, if the caterer is has to remove all of garbage from the location. No matter how you attempt to cut waste, there is waste at any event, and this has to be removed. If you attempted to clear all of this yourself, it could take many trips to the dump and it is worth it to have them remove it for you. Trust me, you don't want to be in charge of this. If they say the charge is a linen cleaning charge but you are given a choice of linens for free, double check and clarify for yourself what is part of your original fee covers what.
The point here is to ask what the 20% covers and if the venue or the caterer can't tell you what it covers then you have an issue. They should be able to describe it to you and not just say it covers miscellaneous, isn't a good enough answer. This is a part of the bill that you can attempt to negotiate. It is worth asking and seeing what they tell you. It is simple, you should be aware of how your money is being spent and what is covered and what isn't. It is your money and you should be okay with how it is being spent.