Self-published and questionable sources about themselves

An important lesson from Wikipedia... and I quote:

Self-published and questionable sources may only be used as sources about themselves, and only if:
 the material used is relevant to the notability of the subject being discussed;
 it is not contentious;
 it is not unduly self-serving;
 it does not involve claims about third parties;
 it does not involve claims about events not directly related to the subject; 
 there is no reasonable doubt as to who authored it;
 the article is not based primarily on such sources.

Emphasis mine. Tiger by the tail?