The worst in my opinion is working with someone who whips up cool shell scripts/utilities, invariably used in production, and uses a "non standard" shell. Usual

The worst in my opinion is working with someone who whips up cool shell scripts/utilities, invariably used in production, and uses a "non standard" shell. Usually checked into source control too. It's just a PITA for everyone else. Same goes for "non standard" command line utilities. If you're writing stuff for your own use fine, but anything shared should be bin/sh, imo.