One cannot. The value of Wikis is that those who do know the answer to a question may post it there, saving others some of the time and effort of reviewing every post in a lengthy thread. This system only works if a large number of people take the time to contribute what they know -and- to update information as it changes.

It will never be the case that every thread will have a Wiki, nor will it ever be the case that all of the information in a Wiki is accurate. The reader will still need to perform his own due diligence before acting. Fortunately, deciding whether to apply again for a credit card is a low risk proposition.

In particular, stating whether a specific credit card is churnable is not a binary Yes/No status. The answer is always it depends, and a well constructed Wiki would lay out a set of factors to consider.