Although charity is giving without receiving anything we do expect something along the lines of a thank-you or something similar, but I think this is unnecessary as then their is a motive to give, and charity should be free from all things expected in return, as it is the removal of something no longer useful to us that is useful to someone else, or the providing of something that is bought for the specific purpose of giving it away.
When we receive something even a thank you, and that is expected it no longer is a free gift but an exchange of goods for words not an exchange of goods for nothing, and we are living in expectation and not the moment. When monks go on alms rounds they remain silent and as a result they are not able to say anything not even a thank-you they are or should be focused on what they are doing not what is being done by others.
Charity should be free from all exchange and completely free to be what it is, not what people want it to be.
At the end of the day I may be right, I may be wrong, but I share this hoping I am one or the other.