Just like these guy say: there are good guy and bad guy everywhere. If for write recommend letter, I think you can't expect professor to write every letter of his students. You know, especially in Tsinghua, so many students could go abroad. So, write and let him sign, that's right, no shame.
I came from Tsinghua. There are someone even steal classmates in the same room. Someone write on desk. Someone just norbaleman of students. But also, some one very gentle, kind and help.