Find a Lemmy app that has user tagging (I use Voyager, and previously Connect) and when you see these users make a note of each one with a red tag so they stand out when you're browsing.
You'll start to see the bastards turning up in all kinds of conversations as well as posting ridiculous shit. That's what I did with the Russian/American trolls/bots during the american election. Very enlightening to see in a political thread who the repeat offender shit-disturbers are so you can down vote, argue with, or report them instead of blocking them and allowing their infection to spread.
Tagging is handy for nice people as well; the community of people around you on Lemmy starts to look more familiar, smaller, and friendlier than you realize, and dick heads become easier to spot.
Everyone wipes down their bathrooms before company comes over, and lives with a layer of TP dust and pubes the rest of the time.