Is it common? Is it knowledge? Among common fans, there is common belief, but not so much knowledge.
Even then, how common is the belief? It wasn't too long ago that the informed population of letsrun readers responded to a "which records are doped" survey, and the "common belief" among these responders was that only 57% believed that El G's records were doped. Or alternatively, a whopping 43% of informed fans believed El G's records were clean.
It's also a common belief that EPO can actually deliver faster 1500m/mile performances, despite the small number of such fast performances during the EPO era. Pre-EPO era athletes like Cram and Coe still remain competitive today -- Jakob Ingebrigtsen did not beat Cram's 3:46.32 from 1985 -- despite three decades of EPO availability and alleged ease, even today, of beating the EPO tests and the ABP, not to mention improvements in shoes and tracks.