Bad Stars is the 171st video made by SuperMarioGlitchy4. It is also the first blooper to feature SuperMarioGlitchy3 as the main villain for a long time since Smg3's plan to kill Smg4 because he felt like it.
The blooper starts off with the Narrator telling a story about Power Stars, which bring happiness to the Mushroom Kingdom, and how there are evil idiots who wish to create an evil Power Star ("Ztar") which would terrorize the Kingdom, but none of them have ever even been seen. It turns out SMG4 is reading the story and he dismisses it as crap, and then throws out of a window, which was one of the biggest mistakes he had ever done. Turns out, right at that time SMG3 was taking "an evil walk" on the Castle Grounds when the book gave him even more brain damage than he already had. He read the book, but thinks it is stupid because it isn't a cookbook or JB Magazine. Then SMG3 reads the part about the Ztar and starts over-reacting about it.
SMG3 is still fangirling over the Ztar by the time he gets back to Bowser's Lair until Bowser tells SMG3 to stop. SMG3 is then determined to create a Ztar. He begins mixing substances and brings it to an orb containg a Power Star. Bowser refuses to help, as he had attempted this before, but it somehow ended up as a hamburger. When they are about to finish, a crazy Toad suddenly appears, and somehow flies into the Ztar's container, declining SMG3's complaint not to go near the Ztar. There is a flash of light, and it is revealed that the Ztar absorbed the Toad, and now holds his consciousness, which it struggles but eventually manages to control. It then breaks free escapes Bowser's Lair, turning all the Power Stars in the world into Ztars on its way to Peach's Castle. Peach finds out, but ends up being knocked unconscious by SMG4's cannon.
Mario and SMG4 run outside the castle to see that the world has had a "darkness" filter put over it. SMG4 blames SMG3 and Bowser when they see the Ztar approaching, and SMG4 tries to get it away. SMG3 and Bowser somehow appear, and Bowser desperately throws SMG3 at the Ztar in an attempt to protect himself, but misses. The Ztar closes in on the group and is about to horrifyingly and painfully kill them, but a Toad appears between the Ztar and the gang. The Toad greets the Ztar, and suddenly, the Toad absorbed by the Ztar takes control of it. When he regains control of his own body back, the Ztar flees, enraged. SMG3 admits he created the Ztar, and agrees to help the gang take it down, after SMG4 threatens him. They come to the conclusion that they must make a "good Star". Back in Bowser's Lair, they use the machine that created the Ztar to create yet another Power Star (which looks like the Ztar at the time, at first), but this time, Bowser throws an Old Man into the Star.
Meanwhile, in Delfino Plaza, the Ztar is wreaking havoc all over town, annihilating everything and everyone. The gang finally locate it, and initiate their plan. While SMG3 distracts the Ztar, Bowser comes charging at it armed with a chainsaw. The Ztar simply teleports Bowser into the ocean, where he explodes. The Ztar continues its pursuit of SMG3. Finally, he lures the Ztar to the gang, and SMG4 fires the Good Star from his cannon, a white Star completely controlled by the Old Man. However, instead of fighting the Ztar, the Good Star rapes the Ztar and soon starts chasing it, leaving everyone in shock, even Bowser. Able to overpower it, the Ztar manages to get away, and SMG4 decides it's time to go with their last resort. Mario uses the cannon, and he fires a Toad towards the Ztar. The Ztar gets overtaken by the Toad, and he begins to converse with the Toad that was shot at it. Unable to keep the Toad within him at bay, the Ztar encounters a Windows XP error, therefore almost subdueing the threat of the Ztar. After the Ztar mentions that it's immortal, the gang decides to get rid of it another way: by tying the Ztar to a cruise boat and shipping him off to the middle of the ocean, taking the Old Man Star with him to ensure that he suffers a terrible fate. The rest of the Power Stars in the Mushroom Kingdom then turn back to normal.