e.g. Ramanuja has said that any Puranic content that disagrees with Vishnu purana is Tamasic. Ramanuja's criterion would make the widespread Narasimha story Tamasic since it occurs only in a rudimentary way in the Vishnu Purana.
But modern scholars regard this classification as invalid.
en.wikipedia.org/wiki/Puranas "Scholars consider the Sattva-Rajas-Tamas classification as "entirely fanciful" and there is nothing in each text that actually justifies this classification."  Ludo Rocher (1986), The Puranas, Otto Harrassowitz Verlag, ISBN 978-3447025225,
Is such classification worth considering?