If you're here, you're hoping I have answers for you - and maybe I do, in a sense!
At the same time, without looking at your particular piece, knowing your particular goals, and being inside your actual, particular head, I can't give you a particular, specific answer to this question.
Rather, I'm hopeful that the following questions can help guide you toward understanding what it is about your hand embroidery that you don't like; who knows, maybe you'll come to the conclusion that your work is actually pretty good!
Does it actually look bad, or are you placing unreasonable standards on yourself?
The first thing I want you to consider is whether your embroidery actually "looks bad," or if you're simply being too hard on yourself.
Certain skills in embroidery, not to mention individual taste and style, can take a lot of time, practice, and patience to develop. What's more, this process necessitates giving yourself permission to start somewhere.
Have you given yourself that permission? Have you accepted that almost none of us are "naturally" perfect at things, especially not right from the start?
If you haven't accepted that yet, you're certainly not alone - I often struggle with this myself, whether I'm learning a new embroidery technique, or some new craft altogether. When that happens, I do my best to revisit the standards I've placed on myself, and to embrace that feeling as part of the process itself.
Have you given yourself time to sleep on it?
A friend of mine once encouraged me to "never unpick at night"; what did she mean by this? She meant that sleeping on a project can often help us get out of our head, and hopefully see things more clearly in the morning.
Maybe you've been looking at and working on your piece too intensely or for too long - try taking a break. Put it away, come back to it when you're rested, and see how you feel about it a day or so later.
Often times, you'll thank yourself for choosing to give yourself a break (vs. ripping the whole thing up in a rage).
Are you comparing yourself to somebody else?
I cannot overestimate the importance of learning to recognize when you are caught in a comparison trap. For some, it can be super easy recognize this pattern emerging. For others, however, it can be hard to admit when we're feeling down due to internal comparisons.
You can get stuck in the comparison trap for all sorts of reasons. For example, maybe you've just seen somebody doing something you wish you had thought of yourself; maybe you were working on a new skill and were reminded of somebody who already knows how to execute it perfectly; or maybe you were reminded of somebody who just seems to have more confidence in their work.
Regardless of the reason, once you find yourself in that trap, it's important to bring your focus back to your own self and your own work. That's how you get out - focusing on yourself.
If you don't pull that focus back to yourself, you may feel yourself pulled to either copy ("I wish I had come up with that; actually, I could have come up with that! I'm just going to lie and say I came up with that!"), or to quit ("What's the point if they're already so much better than me?").*
*Note: There are absolutely a multitude of perfectly valid reasons to quit embroidery; "somebody else is already better than me," is not one of those reasons!
Maybe another opinion might help!
Do you have a go-to friend or partner whose opinion you trust? How about a group chat? Those friends and partners can often help you figure out what's going on with your project - and they don't have to be able to provide you with some sort of critical art-school-level analysis of your work to be helpful, either.
Maybe you think your project looks weird, and a friend can tell you not to worry about it because the "weird" part actually looks like it's on purpose. Maybe you need help choosing between 15 different shades of pink, and a partner can help you narrow that down to just three. Maybe you simply show it to a friend whose initial reaction will tell you everything you need to know. The point is to get used to reaching out, so you can begin developing a support network that works best for you.
Is there something technical getting in the way?
"Hope, I did not sign up for embroidery therapy - I actually just need to know why this looks bad. And yes, it looks bad."
If you are absolutely certain that your hand embroidery looks "bad," at least to you, perhaps something technical is getting in the way. Here are a few things you might consider, if you're convinced that's the case:
Is your fabric tight enough? Loose fabric is great if that's the effect you're going for, but in general it's easier to stitch with fabric that is pulled nice and tight in the hoop. If you're having trouble with this, consider doubling up the fabric in your hoop or binding your inner hoop with fabric. If those options don't work for you, you may need to re-hoop your fabric in a higher quality hoop that will do a better job of holding your fabric.
Are you pulling tightly enough, but not too tightly, on your floss? Pulling tightly enough can be super important (for example, when using satin stitch over a large area). At the same time, if you pull too tightly, you risk buckling and bunching up your fabric; unfortunately, there's only so much an iron can do in that sort of situation, so you may need to unpick and start over.
Does the hoop work as an adequate frame, or does it need to be stained or switched out with something else? Sometimes a plain hoop just isn't the perfect match, frame-wise, for your piece. My go-to solution for this is to put my fabric inside of a hoop that I've stained; you can also find loads of embroidery hoop frames these days, not to mention options such as framing it outside of an embroidery hoop altogether.
Do you maybe need to unpick something and try fewer strands of floss? What about unpicking and trying more strands of floss? If you were hoping it would look daintier, try fewer strands; if you were hoping it would look bolder, try more strands.
Are you using the best stitch to obtain your desired effect, or would something else work better? For example, does that back stitch look fine, but maybe the effect you're going for would be more easily achieved if you smoothed it out with whipping?
Remember: you're not supposed to know all of these potential questions and their potential answers right away. Troubleshooting is a skill in and of itself, and will develop with time, practice, and patience.