If you read papers in the less reputable parts of science (public health, epidemiology...) you'll quickly notice citations going to papers that contradict the c

If you read papers in the less reputable parts of science (public health, epidemiology...) you'll quickly notice citations going to papers that contradict the cited claim, or which are about something totally different, or that don't contain any support for the claim within them. It's common. Peer reviewers don't notice this stuff, journal editors don't either. They might scan read the paper but they aren't checking it adversarially.