Stress
Running a B&B is pretty low on the stress scale. It's not like being an air traffic controller or anything; if you make the bacon too crispy, hundreds of people won't meet their doom.
Still, just as with any job, there's stress to be found. A house full of high-maintenance guests can shoot your stress levels through the roof in no time flat. You'll have to draw firm boundaries with guests who ask too much so as not to run yourself ragged.
B&B owners also have to deal with the same stresses as any small business owner. Ultimately, the buck stops with you. The breakfast has to be cooked; the rooms have to be cleaned; the bills have to get paid. It's all your responsibility, and sometimes, it's no cakewalk.