To be honest I was not expecting this kind of response. Whilst checking a few addresses they seem to be empty, however if I may gweedo, "Yeah, I get tips a lot, cause I am helpful", that provides a fundamental answer.
Listed addresses being empty does not mean that the person has never been tipped, since they could put up a new address after receiving tips. Conversely, an address having bitcoins in it does not mean the person was tipped, the payment could be from something else.