Can't be Dave, because his role was revealed in the newspaper when Tox was blocked.
Can't be Eddie, because his role was revealed in the newspaper when Tox was blocked.
Can't be Suzanne, because her role was revealed in the newspaper when Tox was blocked.
Let's assume the Ghosts checked one of his roles on the first night; what could that have told them?
Lars - Male / IQ: High
Saltzman - Male / IQ: High
Charlie - Male / IQ: High
Cliff - Male / IQ: Average
If it was the first one, then nothing, except that he can't be Jeanette (which is confirmed on the second night). If it was the second one, was there any point in blocking him? No, because Cliff has immunity to being blocked. That leaves Lars, Saltzman, and Charlie. Blocking the Doctor is, in general, justifiable. Blocking Lars and Charlie is not very good. And if they didn't check him and couldn't be sure that he wasn't Cliff, then the target for the block isn't very good, except to prevent the town from getting 100% information.
We can also try to consider the poll from the perspective of these specific roles, because for now, this is still unreliable information.