I have the same problem like this question RestSharp ignores response charset encoding.
But there is no right answer! Code like this
IRestResponse RSP = client.Execute(request);
not like this
Encoding encoding = Encoding.GetEncoding("ISO-8859-1");
var result = encoding.GetString(response.RawBytes);
It means the resetsharp must deserializ the result with right encoding. Someone can help?