This attitude works both ways ,some years back i was #2 on the app at ****** folowing a student in a PA28 he was very low and dragging the thing in , as i taxied in i witnessed a second APP that was a carbon copy of the first.
As i booked in i asked the opps guy if an instructor was watching this student ,at this point the duty instructor was called as it was clear that no one was watching this low time student.
Befor i had a chance to sujest that he view the performance of the student i got a "who the hell are you to coment on ***** students outburst" infact the man was downright rude , to a person that he clearly considered to be an interfearing PPl holder.
At no time did i sujest eny thing other than he view the performance of the student and make his own judgment ,after all you cant see all that your students do and a tip off from another pilot can flag up something that happens when your back is turned.
Unfortunatly this guy put his ego befor the interest of his student and felt that he was not going to take a sujestion from a passing PPL holder.
At all times i kept the convesation as low key as posable but as i departed i did point out that that the person that he was trying to belittle was an QFI with an ATPL and 13 years of instructing time.