Despite how his personality is far from evil, Beerus has does some very awful things both in Dragon Ball Super and the past. Part of it is due to his job being to destroy planets, and another part being his short temper causes him to react rashly in situations that don't really call for it. His laziness is a cause of concern as well, particularly when it comes to Frieza.
What's most concerning about his acts is how few of them involve the destruction of planets. That can at least be rationalized as work, but the way he's treated people or even Kai's is completely inexcusable. More often than not he acts like an angry toddler.
10 Falling Asleep During Universe Hide And Seek
This is very tame compared to many of the acts Beerus has committed, but upsetting a character as powerful and as childish as Zeno is a dangerous proposition. The king of the multiverse often shows little care for life or the universes themselves, having wanted to whittle them down for ages. It makes the fact that Beerus fell asleep (for 50 years no less) during his game of hide and seek incredibly dangerous. It could have very easily spelled the end of universe 7.
9 Slapping Bulma
This one at least had some justification for it, especially when you consider Bulma struck him first. It also led to the awesome, that's my Bulma scene, which showed how far Vegeta has progressed as a character. It was still a little unnecessary when you consider Bulma is the furthest thing from a fighter you can get, ranking at about a .5 on a power scale with Beerus. Deep down though, he may have a little respect for her, considering how often she's willing to challenge him verbally.
8 Using Frieza As An Agent Of Destruction
On one hand, Frieza helped destroy planets, making Beerus's job easier. On the other, he did it with such malice and carelessness that it in turn reflects on Beerus's own lack of care over life.
By allowing Frieza to remain alive, he let him do an unspeakable number of atrocities across the galaxy as his empire grew and grew. The only reason this isn't higher is that they were Frieza's actions rather than his own. While he used him to ease his burden, he didn't order him to commit much of the evilness Frieza did.
7 Leaving The Fate Of The Earth Up To Rock, Paper, Scissors
Beerus isn't that much different from Zeno in terms of lack of care towards planets, leaving earth's destruction up to a game of rock, paper, scissors against Oolong is proof of that. It shows that he can be just as childish as well, doing whatever he could to get his destined battle with the Super Saiyan God. Goku managed to stall long enough for him to get that, but it doesn't change that Beerus was willing to destroy the planet from winning a children's game.
6 Treatment Of King Vegeta
King Vegeta, in many flashbacks, is shown as a very proud man, much like his son. That pride took a major hit when Beerus came to visit the planet. First, Beerus used the king's head as a footrest during the feast that was prepared for him. As if that wasn't indignity enough, he punished the king for taking the most comfortable pillow in the universe. It all shows just how petty Beerus can be when he wants to be, showing little respect to the things given to him.
5 Ordering Planet Vegeta's Destruction
This one is a little lower because Beerus only gave his consent rather than doing the deed himself. That achievement will always belong to Frieza and his fear of a Super Saiyan.
Beerus's involvement feels incredibly shoehorned in anyway, cheapening a bit of the paranoia Frieza had. Regardless, it still shows the casual disregard that Beerus has for planets as well as why you always want to try to stay on his good side.
4 Destroying King Kai's Planet
This event has so many variations to it that it may as well be the Joker's back story. Depending on who you talk to, the planet was destroyed because King Kai beat him in a car racing video game or hide and seek. In Beerus's words, he destroyed it because he didn't like the food there. No matter which version is true, they all make Beerus look like an ass. Destroying someone's planet over something so trivial makes it seem like Beerus was throwing a temper tantrum.
3 Sealing Old Kai In The Z Sword
Beerus isn't a man that you want to have disputes with, that's a fact that gets proven time and again throughout Super. He has little patience for them, and when his patience runs out, you're not going to like the results. The fact that he sealed Old Kai away for what is described as a trifling situation is proof of that. More than likely the kai's were trying to get Beerus to do something he didn't want to, and that led to him reminding them how powerful he was.
2 Destroying Half A Planet Because Of Greasy Food
This happens at the start of the saga introducing him, showing Beerus compliment and even enjoy the food on a planet filled with pig-like humanoids. The problem was he felt it had too much grease, meaning he'd be sluggish and lethargic the rest of the day, something he couldn't allow. He went on to destroy half the planet with a mere tap of his finger, saying that he was doing the universe a favor, despite Whis saying his actions were unfair.
1 Nearly Ending The Universe Over A Piece Of Fruit
Beerus and Champa have a less than stellar relationship with one another, and that's putting it lightly. One day they nearly ended up destroying the entire universe because Beerus ate the only Puff-Puff fruit on his birthday cake which infuriated Champa. Their battle ended up destroying multiple planets as it spanned across the universe. When told it could destroy everything, they both stated that they didn't care, forcing their attendants to break it up.