There is so much. He got elected by lying about his opponent, which might not seem as such extraordinary thing, but this is actually statement penned by our highest court - they were ruling about the fairness and validity of the election and they specifically said, that Zeman knowingly lied multiple times, but the elections are valid anyway. Bottom line, he's a liar in the eyes of our highest court, not many politicians have this kind of privilege.
He's extremely vain person. He's giving our highest state honors to his friends and to people who supported him during his presidential campaign, but actually decline to give a man who opposed him during the elections his rightfully earned highest academical degree (professor) even though he has no right to do so, since he's got only ceremonial duties in this regard.
He said about one of our most gifted and valued journalist of 20th century - Ferdinad Peroutka - that he wrote an article called "Hitler is a gentleman" where he has supposed to appreciate Adolf Hitler. Peroutka was in concentration camp during the war because of his opinions. His granddaughter get this whole thing to court and the court said there is no such article and Zeman should apologize. He ignores the court and haven't apologized to this day.
He did complete turnaround of our foreign policy. I would like to think, that if anything, Czech Rep. was known in the world for Vaclav Havel and his humanitarian values. Zeman on the other hand is trying to shift our nation to Russia and China, he's got financial ties to Russian Lukoil and China (which is the reason for this whole Dalai Lama fiasco). He's shiting on Havel's legacy and is so far up Putin's ass it's really disgusting.
He has no respect for the office, for example he showed up drunk at the showing of our crown jewels which is a yearly event and is really sort of a big deal. His alcoholism gets in the way of his function as a president.
There is so so so much more, but you get the idea of what kind of a man he is. If you are in for more this wiki article sums up some of his other controversies
https://en.wikipedia.org/wiki/Milo%C....93_present.29