New players astound me with their lack of common sense sometimes, but it's not a huge deal. I'll tell em to get out of hard/suicidal or whatever I happen to be playing, explain why, and kick them. Frustrating to lose 75% of HARD games simply because everyone dies and leaves, cycling around 20 players through each game, but I can't really say I hate them.
The people who actually bug me are those who think they're extremely knowledgeable despite having bought the game a couple weeks ago. Some level 5 support tried to explain to me how to finish off scrakes with a hunting shotgun; acted like he discovered selling and rebuying weapons, and uses $10 shells on anything including headless, distant, single clots and bloats.
Although it's quite fun to have a fellow demo tell me how the LAW is useless on hard, when I then outscore him in kills and saving our teammates' asses.
Oh, right, totally forgot one. People who don't talk, and act like it's a solo game. Someone waltzes in, buys their equipment, accepting your cash without looking at you, and wanders off to the other end of the map. Usually they die and leave, while everyone else is trying to get them to explain what the hell they're doing. Makes you wonder if they don't speak English, or really can't find out what the chat key is.
I just bought this game like a week ago so don't get mad at me for not understanding something, but i don't see how that effects you. So why do you care? I typically choose which ever weapon I'm in the mood for.
Your presence in a server increases the life of zombies, and number of them. By being there you're making the game harder for everyone, so you should be prepared to carry your own weight. When you're playing as a sharpshooter with a shotgun, you could be doing much better with a handcannon aiming for the head. Alternatively, you could simply buy the shotgun like you wanted and switch your perk to support (YES, YOU CAN SWITCH PERKS MIDGAME. YOU ARE NOT STUCK WITH ONE THE ENTIRE ROUND.) You lose nothing by switching and might actually be helpful and able to protect yourself and others, instead of having other players babysit you or leave you to die.