|When you assume, you make an ass out of u and me.
Don't assume things; be skeptical about everything. This applies to people, as well as news: don't "assume good faith", and don't assume bad faith. Also don't assume worse, or better, faith than the situation warrants.
Criticize freely whenever there's reason to do so — and apply the principle "never assume" to your criticisms: don't needlessly criticize more than is actually relevant. Suspicions too can be voiced, but again, don't do so needlessly. Be skeptical about your suspicions; keep in mind that you can push others into worse behavior; and when you're on the receiving end, be skeptical to avoid reading too much into others' criticisms.
Rejecting an unverified submission does not involve any assumption. The submission isn't being rejected for being false, it's being rejected for lacking verification. We don't "presume falsehood" until verified — we factually observe it hasn't been verified, until verified.
When criticizing submitted work, if there's no reason to also criticize the author, don't. When someone else criticizes your work, don't take that as criticism of you.
Other contributors edit
Welcoming new contributors and maintaining a friendly atmosphere on the project does not involve any assumption. Treat people as well as circumstances allow, even when (as will sometimes, sadly, happen) it becomes necessary to escort them to the exit. You don't have to naïvely trust people in order to treat them with respect, or in order to help them learn what they should be doing.
The English Wikinews is based on trust — we are a meritocracy based not on naïve trust, but on informed trust. Each individual Wikinewsie gradually accumulates reputation — for honesty, for integrity, and, yes, for ability — and on the basis of their reputation, the community may choose to entrust them with various special privileges on the site. Declining to grant privileges does not require any assumption: just as a contribution has to be verified for publication, a contributor must earn a reputation to be granted special site privileges. Declining to grant privileges does not in itself imply lack of respect, either.