Bad hygiene. Seriously people, wash your hands, take showers, and brush your teeth. Its not that hard.
Other than that, nothing bothers me. Vomit, urine, blood, and other bodily fluids/functions are all a part of a an athletic trainer's daily life. Actually, most of us get excited when somebody has an accumulation of blood under an ingrown toenail and we have to drill a hole through it to relieve the pressure. Or if someone has the stomach bug and hasnt been able to keep anything down for a few days, we love hearing all about it. And we usually end up telling other athletic trainers our stories. Its just our life. Our sick, germy lives. XD