I take it you have not read H.L.Mencken's reporting on party conventions in the 1920s. I was a bit incredulous of delegations cheering speeches by marching around the aisles for ten or twenty minutes, but I suppose there was no point in misreporting that ...

No good link in a quick search, but perhaps starting from here: https://www.dclibrary.org/node/32107

Edit: There's a sample down from the page heading "416 A Mencken Chrestomathy" in https://biblio.wiki/wiki/A_Mencken_Chrestomathy . Other books had much fuller accounts of several conventions he reported on.