I don't know that anyone who has been hunting and dressing their own deer for any matter of time can say they have never accidentally hit the paunch or intestines at one time or another. It happens. If you are careful it doesn't have to ruin the meat. You might have to trim the infected areas away before you butcher it though.
I plan on having my wife help me do our first one in the field. She was a bio major in college who could skin a squirrel or cat so that the skin looked like clothing (she's shown me pictures, very creepy). She does the fish we catch now and is almost surgical in the cutting of them, and likes to check out the organs once she's done. Her and the daughter were discussing the stomach contents of the catfish she got at Brookville last week after she cleaned it.