Guys that are consistently late for crew change. Understand, flights can get delayed/overbooking, etc. Why it happens to the same people is a pattern in my eyes. Most of our reliefs made a good effort to get to the vessel on time. These men want to get off, and arrive home at a timely hour. Noon or close to it is not a hard request to meet. Nowadays in this virus thing, gonna have to be flexible, but not more than a few months ago, you can get there on time. Cured that after a bit Kraken, by being a bigger asshole than the other assholes trying to take advantage of my crew… Told my crew to relieve them the same time they were relieved . Problem went away in not too much time. All the things you mention Hooligansailor are on my list too. The fishy handshakes are up there.
I will say the handshake thing is a big one with me. My granddad always said that you give a firm handshake and look a man in the eyes and you’ll be able to take his measure in his return. Can’t be doing when it’s like shaking a wet noodle about!
Hygiene is probably the biggest one for me. Working in the Engine Room it gets hotter than hell downstairs at times and if I suspect one of my lot isn’t showering enough, they’re going to get told. No-one wants to walk into the mess room and be greeted with someone rank with sweat!