it all depends. i lent thousands of dollars ($6000 accumulated) to friends that swore they would pay me back. he quit his job and the other went on a vacation. one never thanked me. and said racist things. the other was only thankful but didn't pay me back because i helped him with his assault case by taking photos of his broken jaw.
now, i heard about a professor giving a student $100 because the student came to him for help. what a nice jester.
but if they claim to pay you back and not pay you back that's two faced.