You might be a crappy coworker if...
You don't respond to emails, phone calls or other correspondence in a timely fashion. Your coworkers need you to respond. Now, there's plenty of resources about managing emails (See: Getting Things Done), so "drowning in your inbox" isn't an excuse. When you receive an email, think about who else needs to know about it, and what action should be taken.
You are a bottle neck for project flow. If other people are constantly waiting for you to do your part, you're a bottle neck. Try this: when you're starting your day, find the tasks and projects that OTHER PEOPLE need you to do, and do those items first.
You respond to coworkers with "That's not my job" and/or "I'm too busy for that." We're all busy and we all have "other duties as assigned" in our job description. If you're too busy to do your job, talk to your manager about your workload. I bet you're spending time on things that don't matter instead of things that do. And yeah, certain tasks might not be actually written in your job description, but sometimes a project is a team effort and you have a part to play in that. I'm not saying you should do other people's jobs FOR THEM. I'm saying - don't be a jerk about chipping in once in a while.
You stink. Literally. If you wear perfume or cologne to work, you're probably a crappy coworker. I mean, why? Why do you smell like that? Who are you trying to impress? This goes for bad smelling laundry detergent, dryer sheets, soap, hair spray, etc. Whatever is making you smell bad. Gross. Also, that stinky lunch you're eating at your desk? Stop it. That fish you microwaved? Stop it. Stop stinking up the place. I once worked with a guy that I could smell before I could see him. That's a problem.
You treat people that don't look like you differently. This is illegal. Discrimination is not ok, ever. As someone who has been discriminated against and treated differently than older, male coworkers, this creates an unfair, uncomfortable and unproductive work environment.
You do work that isn't your best. Just try to do your best. No one is perfect. But you're a crappy coworker if you consistently don't try to do your best.
You're late. Being late is a sign of disrespect. It shows you don't care about your coworkers or value their time. Early is on time and on time is late... and late is a big FU.
You're unprepared. Bring a pen and paper (or laptop) to meetings. Bring relevant notes and knowledge (be prepared). Bring a calculator if it makes sense. Bring a water bottle and/or coffee thermos. Whatever you need to be the most attentive and productive member of that meeting, bring it.
You're not respectful of shared space and individual boundaries. If you work in an office, warehouse, or otherwise, you probably have a small dedicated space to do your work, and some type of shared space with your coworkers. If you're approaching someone's individual space, do so with respect. Knock on their door or cubicle wall, ask to enter or if you can interrupt, and be efficient with your time. In shared spaces (lunchroom, break room, bathroom, conference room), clean up after yourself. If you need to talk to a coworker about a work issue while they are on their break, ask them if that's ok before launching into your issue. Also, use an appropriate volume of your voice when you're on the phone or talking with someone.
You need to be reminded all the time and you don't listen. How ever you manage tasks, projects and your calendar is fine by me. But, you've got to manage it. If you don't know how, ask for help. Listen, pay attention, and follow through. Respond. Look people in the eyes.
You suck at your job. Some people end up in jobs that just aren't a good fit for them. If you just don't know how to do your job, talk to your manager. Or learn. Or do better. Or get a different job. But don't stay in a job you suck at. It's not good for your coworkers and it can't possibly be enjoyable for you.
How to Be an Awesome Coworker
Try your best. That's all anyone is asking from you. If it's not your best, try harder.
Learn. If you're not good at something, learn. Or do something else. But don't just keep being bad at it. That's not fun or productive.
Listen, respond, and follow through. Be open and receptive to feedback. Be willing to help others, and you'll get the help you need from them.
Treat others with respect. This is just a general life best practice. Don't be a jerk. Have basic manners - say please and thank you. You know, be a nice human, eh?
Smell like nothing. The smell of nothing means you are clean without chemicals.