I believe there may be two types of mis- information being discussed.

The first is mis transcription of the original documents, or error made in the original documents. I have had many mis transcriptionof the original documents corrected by sending documentation for why you believe there is a mis transcription to Ancestry. Remember some of the database do not belong to Ancestry and they have no control of the information. There are many digitized WPA databases on Ancestry. WPA ended in the 1940's.

The second type of mis information is found in the online trees. Many of them are hopeless and there is not much of a chance of getting the owner to correct his tree, IF he is still around.

If there are a few errors in the tree, and it looks like the owner is trying to provide a well documented tree, contact him through the Ancestry Contact system. Send you references (Links if possilbe) to the documents that show the errors in his tree. When name collectors are involved it make take several contacts to the tree owners before you find the owner who actually created the original tree with the error.

Some time it may take years, but eventually you will see the corrections. Once one person makes the correct, the name collector's trees will eventually change also.

I had a situation where I had several documents that I had gave a person parents. There were two people of the same name, but different parents living about 3 miles apart. I only made head way in getting the correct parents, when new information was added to FamilySearch that proved the owners wrong. Again I sent the links to the correct data. I also offered copies of all of my documentation.