This... is why you don't tell students they're competent when they're not

... well, one good reason, other than the fact that you're lying to them...

http://www.lawnix.com/cases/vokes-arthur-murray.html

A woman sued her dance teachers because she couldn't learn to dance—and won!
// OMG Facts
A woman sued her dance teachers because she couldn't learn to dance—and won!

A lady only known as Ms. Vokes decided to become an accomplished professional dancer at the mature age of 51. She signed up for dancing lessons at Arthur Murray Dance School and attended classes diligently for a couple of years.

The employees praised her skills and flattered her into believing that a professional dance career was well within her grasp. Arthur Murray even convinced her to sign up for $31,000 in dance lessons.

But the sad truth was that Ms. Vokes had no potential whatsoever, and she was not making any real progress. In truth, she had absolutely no skill as a dancer and was rather uncoordinated. When she finally realized that she will never be the next Ginger Rogers, she decided to sue Arthur Murray for misrepresenting her skill as a dancer.

The court ruled in favor of Ms. Vokes, saying that Arthur Murray Dance School employees had superior knowledge of dancing and had a duty to inform Ms. Vokes that she did not have any dance potential. The court held that, because of the sheer volume of flattery and the large amount of money they received, Arthur Murray had a duty to be honest with Vokes.

Arthur Murray was ordered to pay her over $30,000 for fraudulently telling her that she can dance.

(Source)