In this article†, Edward Hibbert (who plays Gil Chesterton), describes his character:
Gil’s effete and affected with a wash-dish tongue.
What is meant by a "wash-dish tongue?
Note: Googling "wash-dish tongue" returns only the article I have linked, and this question. Also "wash-dish" does not appear as a result in dictionary.com.
† Which, if you are a fan of Frasier, you really should have a read, because it is excellent.