Earlier quoted context omitted.
As a counterpoint, one of the most useful customizations I've made to my prompt is to emit the exit status of the prior command. Knowing that something failed is a useful signal, esp. when sometimes the thing failing just fails to emit any output that indicates that it failed. I only emit it if the prior command fails, too, so it doesn't clutter things the 90% of the time things are working. » true » false (last comm…
Oh, how do you automate that? I usually add a "& say done | say failed" to long-running tasks if I remember to do it.
For example the following prints the exit code in green if zero, in red otherwise:
PS1='\[\e[$(($??31:32))m\]$? \[\e[39m\]'