I can't think of many T's who'd outright say F's were 'demonic'. But quite a lot would probably say they can be difficult to deal with (from the T's POV obviously) and so their opinions are more to do with utility, strategy, analysis sorta thing than deciding or saying whether a person is good or bad as a person.
Personally thoughts of whether someone's good or bad rarely enter my head, including when it comes to when I'm deciding what sort of dealings I'd like to have with them.
It's all the more intriguing then that the title that got me thinking "that's EXACTLY the kind of wrong assessment of my assessment that a Feeler would make!" was actually by a Thinker!