I can count the number of times on one hand that I've run into truly bad or rude divers. I automatically discount new divers who just don't know what they are doing, after all we have all been there, so they get a pass.
The one I recall the most was the Manhattan lawyer and his two girlfriends on a boat in Hawaii. He had a scimitar strapped to his leg and all this brand new fancy gear - including a Shark Shield. He made a big deal about telling us how he was protecting us from the sharks, and not to touch the cable. He'd clearly spent a ton of money outfitting himself and his harem. Some of their gear still had tags on it. Despite the money issue, he was an ok diver overall.
Girlfriend #1 made a big drama about being vegetarian, though they didn't warn the dive boat in advance. So all she ate was the Oreo cookies and soda. Irritated the crew to no end, but they took it quietly.
Girlfriend #2 was the nicest, but turned out to be a dive bomber. I had just finished my descent and levelled off about three feet off the bottom when I was hit by what I thought at first was the anchor. The weight slammed me into the rocks and pinned me there. A few seconds later the weight was removed and I saw the DM helping GF#2 by taking some lead off her belt. At first, I was wondering why he was giving her all the attention when she slammed into me, but I figured it out later back on the boat.
Turns out the DM was the shop owner, and he'd been paid big bucks by the lawyer to film the threesome and show them a good time. All other priorities rescinded.