Is the Druid extremely unreliable for everyone else? I regularly see the Druid say there are NO outcasts when selecting, say, the Bombardier or the Plague Doctor, and not only are those characters not in disguise (i.e. they're exactly what they look like), but the Druid has not been corrupted, so they should be able to correctly identify those characters. This happens regularly, it's gotten to the point that I don't even bother using the Druid's ability most of the time.
I haven’t seen the druid behave like that. Evil minions sometimes disguise as outcasts, so if the druid is saying there are no outcasts, the outcast might be a minion in disguise. (Demons have a special rule that says they can’t disguise as outcasts or share disguises with a truthful/corrupt but good villager - they are one of a kind or sharing a disguise with the drunk or another evil.)
The only time I’ve seen a truthful druid say there are no outcasts when there is one is when I point the druid at a wretch … but that’s supposed to happen because the wretch looks like an evil minion to all the other characters, not a wretch. If a druid says they see a wretch, they are lying.
Edit: This assumes you are playing the itch web version. If you are talking abut steam, there are new cards and bugs that may cause too many outcasts to appear.