1. They want their code to act as their resume. These people put a ton of effort in to making their code work well, look good and read nicely.
2. They genuinely believe in the Open Source movement, and want to share what they build so other people can add to it, improve it, and use it more freely. Their code looks good and reads well, but often not as well as the people in group 1 because the results actually matter more than the code.
3. Pure vanity. They want to be famous and think making their code open is a way to build their rep. They'll give things a bit of polish before putting it on Github, but often quality is second to quantity.
4. They put things on public repos without really caring whether anyone sees the code because they write the code for themselves, so it's technically open source but only because it's not private. The code is usually really hacky but no one sees it so it doesn't matter.
By the sounds of things you're in the second group. In your position I'd tidy up the code as best as I can but I wouldn't stress if it's not the best there is.
(I'm in group 4)