In the damning-with-faint-praise department, this from Robert Dallek’s An Unfinished Life (discussing John F. Kennedy as a sophomore at Harvard):

“Though his mind is still undisciplined,” [JFK's] tutor wrote, “and will probably never be very original, he has ability, I think, and gives promise of development.”

An Unfinished Life, page 43.

The moral?  There’s always room for improvement. Everyone can learn life’s best practices.