Assuming good faith is a fundamental rule on the Scratch Wiki.
Good faith and bad faith
Good faith is honest, sincere, and law-abiding intentions, regardless of the outcome. The opposite of good faith is bad faith, which is the intent of deception, fraud, and vandalism.
Good faith on the wiki
Assuming good faith is a rule that states to assume that editors' edits, posts, and any actions they do on the wiki are made with sincere intentions. In other words, assume that all edits one makes are because they think that it will help the wiki, not destroy it. Take note that assuming good faith does not mean that one does not have the right to revert edits or use evidence to back up points; it is merely a guideline to prevent more conflicts. When an edit breaks the guidelines but it is not obvious if the editor's intentions were only to harm the wiki (such as repeated offences and vandalism, in which the editor may be acting in bad faith), do the appropriate actions to the edit (such as reverting it) and kindly explain and resolve the problem. Doing so will allow the editor to learn from their mistakes. Continue to assume good faith until the conflict is solved.
Assuming good faith is extremely important towards newcomers. A newcomer's edits may seem reasonable to them, yet they can still break the wiki guidelines or editing conventions. As such, do not criticize newcomers harshly, as all new users are valuable contributors; instead, calmly explain what they did wrong and how to avoid it in the future. They probably didn't mean to do any harm.
What "good faith" does not mean
Good faith does not mean that you have to accept all edits without question. It just means that you have to recognize that the editor probably meant no harm. This rule does not mean you have to agree with the editor and are not allowed to undo the edit if applicable rules apply.
Bad faith on the wiki
Editors in bad faith are usually more mean, so do not lose your composure. Instead, tell an administrator or any user listed in the guidelines to get their help to deal with the situation. If no admin does any action in a few days, talk to the editor calmly, and provide sufficient evidence in the form of edit differences or permalinks. Remember, bureaucrats cannot act on claims until acceptable evidence is given.