Problem
When trying to execute something against a web service, you receive the following error message:
Client found response content type of 'text/html; charset=utf-8', but expected 'text/xml'
In addition to the above error message, you may also receive text that indicates that customErrors need to be set to 'Off', if you wish to see the real error message.
Solution
The "Client found response content type of 'text/html; charset=utf-8', but expected 'text/xml'" error message is a red herring. It is true that the response was not in the expected format, but the real issue is descrebed in the "improperly" formatted response. In my case, because the web service's web.config file had customErrors set to "RemoteOnly", I had change this value to "Off" in order to see the real error message. The real issue had to do with permissions and was specific to the web service I was dealing with.