Has anyone ever heard of an instance where somebody from a race of telepaths (for example, Betazeds) tried to read the thoughts of a changeling posing as a solid and what the results were? Could a changeling somehow hide its identity without giving itself away?
We know from DS9: Fascination that a powerful telepath (Lwaxana Troi) is unable to read our resident changeling, Odo:
LWAXANA : What is it, Odo? (off his reaction) I may not be able to read your emotions, but I can read your expression. Something's wrong.
However, we see in DS9 : Things Past that changelings (as a species) actually have quite a substantial telepathic ability:
ODO : (off PADD) The plasma storm that hit the runabout activated the enzymes and initiated a telepathic response.
BASHIR : Your mind reached out to find other changelings to form the Link, but it could only find Dax, Sisko and Garak.
I think it's reasonable to assume that a more experienced changeling would be able to control that telepathic ability to perfectly mimic a human (or alien) mind, at least sufficiently to fool a Betazoid scan.