I take great care to avoid nicking the guts. Yes, you can wash the meat if you do nick something, but getting all the bacteria out of the body cavity is pretty nearly impossible, so for me it's worth the extra time to avoid that contamination in the first place.
I also like to clean off the caracass after plucking and before gutting, so contamination isn't transferred from the skin to the insides. I think if you take reasonable care this way you will end up with a carcass that is much, much cleaner than anything in the store. Since I prefer to let the carcasses rest for 24 to 48 hours before freezing, to let the muscles relax so the meat is more tender, having a really clean carcass is important to me. The inside is more important than the outside IMO, because the outside is always exposed to more heat during cooking.