No* wiki sources should *ever* be considered as a primary source.
This includes things like Wikipedia, Wookieepedia, HP Wikia, Buffy Wikia, Marvel Cinematic Wikia, and IMDB.
Talk to any educator, and you'll hear about students trying to use Wikipedia or similar sources as references for their papers. As these students are told, resources like Wikipedia are fine as starting points, but not for actual citations.
Many wikia sources are full of citations. Wikipedia, itself, is full of citations that can be cross referenced. Wookieepedia is also often well referenced. Other times, not so much.
No* wiki sources should *ever* be considered as a primary source, not even us.
Our answers should be cited with verifiable references. That means linking to definitive, verifiable sources. We should be linking to the sources that the wikis linked, not the wikis themselves.
Sometimes all you've got is a wiki.
Sometimes there are unsourced "facts". That doesn't necessarily mean they're wrong. I'm ok with people mentioning these facts, so long as they also mention that the claim is unverified. I won't downvote answers based on these facts, but they're not getting an upvote from me either.
Sometimes passages from wiki sources are acceptable.
If there is a verifiable citation to match them, sometimes Wiki sources have great summations of facts. In these cases, I find it acceptable to quote a passage from a wiki source. Sometimes someone else has already said it far better than I ever could.
What is acceptable should be left up to the person asking the question.
rules guidelines above, I hesitate to ever say we need a "consensus" or any sort of official rule about whether wiki sources are acceptable. A poor, unsourced answer is still an answer. It may deserve a downvote, but I would not vote to delete just because it's an unsourced statement.
*Some official wiki type sources like Marvel Universe are more acceptable as they are curated by employees of the company.