Bulma is one of the smartest characters in all of Dragon Ball (as hard as that is to imagine sometimes), more tech-savvy than just about every character, save for maybe her father. At a young age, she was already making things like the Dragon Radar, and now that she's older, she's ramped up the technological achievements.
In the same breath, she lacks a lot of common sense in situations, doing things that don't make a whole lot of sense. Most of this is due to her character just being a selfish teenager for two-thirds of the series.
10 Genius: Making The Dragon Radar
This device is one of the most important inventions in the entire series, serving as the only way to find the Dragon Balls in the world. It's a device that doesn't work on just earth either, it's tracking working just fine on Namek as well.
It's amazing in itself that something like this could even be made, but then you consider just how young Bulma was when she did. She was no older than 15 at the time, yet, she was able to craft something that's remained useful for the entire series.
9 Not: Her Choice In Men
Admittedly, this ends up working out in the end as Vegeta ended up not only being a good husband but a good father as well. Bulma's choices in men still leaves a lot to be desired though. She was often enamored with any sort of bad, or pretty boy, no matter what it is they did.
She was swooning for Zarbon during the Namek saga and even forgave Vegeta for lapsing back into his sense of villainy during the Buu saga. Even Yamcha was a bandit trying to steal the Dragon Balls at the time she fell for him.
8 Genius: Great Saiyaman Watch
She managed to craft a watch for Gohan that was akin to the briefcase Iron Man used in the second movie. It's a watch that lets him switch seamlessly into his costume in a manner of moments. If that wasn't enough, she also helped develop the costume itself. Considering how fashion-forward she is, it's a costume that isn't ecstatically appealing, to say the least.
What's most shocking isn't even that she helped with this, it's that she did it in under two hours. That's an incredibly short amount of time. We've all watching enough Spider-Man movies to know how long it can take to come up with a good superhero outfit.
7 Not: Wanting To Use The Dragon Balls To Wish For A Boyfriend
This one plays a little bit into her being young at the time, but even then, it's more than a little head-scratching. Bulma's an attractive girl in that universe and not just because Roshi wanted to go on long walks with her.
She was able to flirt and use her sex appeal to get plenty of things throughout the series. Why then did she ever think she needed the Dragon Balls to get a boyfriend? It couldn't have been that hard for her to find one at school.
6 Genius: Repairing The Scouter
Once Raditz was dealt with, the entire Z warrior team got their hands on his scouter. In true Bulma fashion, it didn't take her long to repair it, despite it being a technology that she was unfamiliar with.
It led to a pretty humorous scene where she read out everyone's power levels, showing how long some of those present were. While it didn't get much play in the series beyond the Namek saga, it's still interesting that she was even able to use the thing.
5 Not: Standing Up To Gods
This happened not once, but twice during Super and admittedly, both times were pretty cool to see considering how her character used to act in these situations. Unfortunately, that doesn't make either of them less dumb. As a normal human without a shred of combat prowess, one shouldn't try to strike a God of Destruction nor back talk Zamasu, a being who utterly detested humanity.
It at least showed that Bulma had grown a lot as a character, willing to act rather than simply complain. Both cases ended as you'd expect though, Bulma being put in her place.
4 Genius: Building A Time Machine
This a combination between both Future Bulma and the present day one we all know. Future Bulma was the one who originally created it, sending Trunks back in time to help stop the androids and later Goku Black.
Present Bulma meanwhile was able to repair it on more than one occasion, showing the intelligence of both is the same. Bulma's ability to use foreign technology may be her biggest achievement as a character, oftentimes being the only one that can manage it.
3 Not: Talking With A Frog
Now she had no way of telling that this frog was Ginyu, but the fact she went from being completely grossed out by the amphibians when they first surround her to wanting to rig a device to talk to one of them is weird.
Granted, she was certainly under a lot of stress on Namek, being abandoned by Krillin and Gohan, but that doesn't equate to needing to speak to animals. What was she even expecting them to say? The fact it was Ginyu who subsequently took her body, was just icing on the cake.
2 Genius: Creating A Device To Speak To Animals
While the reason for it wasn't her brightest moment, the fact she could whip up a device like that on the spot is incredibly impressive. It's hard to gauge time during the Freiza arc since five minutes took about five hours in run time, but it's safe to assume she made the device in under an hour.
It's the perfect example of what a genius she could be when she applied herself to it. Imagine what she could have made if she actually had proper supplies at the time.
1 Not: Lengths She's Willing To Go To Get What She Wants
When she struggles to get the job done, she almost always reverts to using her feminine wiles tow win others over. Within the first three or four episodes, she tries twice, once on Goku and once on Master Roshi, to varying degrees of success.
As you'd expect, Roshi is completely smitten, and easily taken in by it. Goku on the other hand doesn't even understand what's going on. It was a bit short-sighted of her to assume that this tactic would work on someone as young as Goku.