Quite often I browse code of some small Android applications that are posted on Reddit, in articles, in weekly newsletters, and wherever they catch my eye. Maybe I'll see some trick, catch onto some idea and develop it in my head into something interesting. And this is usually approximately like roulette, where you're betting your free time on zero.
One of the main life hacks to save time: if you see ExampleUnitTest with ExampleInstrumentedTest in the project, you can safely close the project, it's a red flag, there won't be anything interesting there.
I'm joking, of course. But actually this isn't far from the truth. I don't like when tests are left (I don't even expect people on the internet to write them anymore), when some auto-generated comments stand exactly in the same place where they were from the moment the project was created, when commits are named carelessly just because it won't let you commit with an empty message. Hygiene in daily work is arguably more important than everything else. Sometimes you can turn a blind eye to this, time is being spent, everyone understands everything. But if you're posting a project publicly saying "look what I made!" or listing it in your resume as an example of work, then clean up, please.