kaka happens.
There are some nursing roles where nurses do not clean poop, but poop will be inevitably part of your education.
But like someone else posted, you will get to the point where you clean it up, go eat a sweet potato casserole and talk shop, too. Really.
Focus on the person--their skin, their situation and learn to plug your nose and it can all be endured. For some of us, poop isn't as adverse as mucus or (in the ED) freshly consumed and regurgitated pizza and beer (or spaghetti--do you think people *plan* their diets before they have a MVA?)
But truly, this is a "don't rush things" issue. When the time comes, you'll make it (or you won't) but secretions are not the only thing or even the best thing about nursing. They are merely a part of it.
BTW, my hubby is a doc and he does poop and vomit when he has to--both at home

and in the work place. He started as an orderly and knows the drill. However, I have known more docs who didn't.