When you are talking about data there are lots of issues beyond simply getting continuity on the right leads. Most residential users might not reallky notice things like Near End Cross Talk and reduced data rates because they are not hitting the LAN that hard and don't really know what "good" is but if they do figure out they are having 50% packet loss because of a staple in the Cat 5 behind a wall or a poorly made up keystone, they won't be a happy customer.
