Nothing wrong with logging pax flights, or "failure to launch" flights of-course, particularly as with that CPL student where he learned something.
It's counting the hours that's a problem.
I have quite a few such flights in my logbook - but I don't include the flight time in any totals, that's all. Where I got an hour in the back of a Yak-52, or abandoned a flight after a nosewheel steering failure - I learned stuff and remember it. But, they're not in my totals, just there as part of my flying memory.
I have seen one in tears when told that all his club check outs were actually dual not PICUS. Meant his ATPL skills test was invalid and he would have to wait another year
Grief, how many checkouts had he done!
G