flannel-mouthed

adjective3

1. •
   Possessing, characterized by, or in the manner of speaking of a flannelmouth.
2. •
   Smooth and persuasive in speech, especially in order to deceive or manipulate.

   • I went to her, sat close beside her and tried snuggling up a little. It worked. . . . "I can get them," I said just as flannel-mouthed as ever I could, like all of us talked to her now. — 1913
3. •
   Unclear, muffled, or halting in speech.