An answer I gave was deleted by a moderator. The question asked specifically about the validity of a single source, which claimed to be a clinical study of an alternative medicine treatment.
My answer discussed the experiment this study did, and stated that the experiment was not valid.
The first reason the moderator gave for deleting my answer was, "Firstly: you provide no evidence, you only cite their study."
The question asked "Does the study described on the product website support the claim that the product prevents sunburn?"
Is it skeptics.se policy that an answer must cite more than one source?
Related, but concerning a single high quality source.