Whether his intentions were good or bad in Villar's case, Revillame is a tv personality--a celebrity one might say. Thus, he has negative impact because "celebritism" or glorification of politics and government is rarely a good focus. Furthermore, Revillame's history with "meddling" with politics is not the brightest. His intentions with Villar's candidacy may seem suspicous between the two and affect the voters for his side, or against his side; still the politics are glorified and unnecessarily focused upon. Albeit, I do not live in the Phillippines and do not understand the politics system there.
No. When a popular public figure endorses a particular candidate, it only temporarily hurts the other respective candidate. At the end of any particular election, one would like to think that the public votes for the candidate that they feel will best do the job they are being elected to do.