We make very careful considerations about the interface and operation of the GNU coreutils, but unfortunately due to backwards compatibility reasons, some behaviours or defaults [pixelbeat.org] of these utilities can be confusing [pixelbeat.org].
This information will continue to be updated and overlaps somewhat with the coreutils FAQ [gnu.org], with this list focusing on less frequent potential issues.
Good tips and reminders for those who don't work mostly on the CLI.