"I wanted to clean here."
Translation:Chciałem tu posprzątać.
Is there a good reason why "Chciałem tu sprzątać" is wrong? Isn't it just a different emphasis (on the action not the outcome)?
Sprzątać - stress the act of cleaning, posprzątać shere information about starting AND finishing cleaning. We call that "czasowniki dokonane i niedokonane".
Not really. First, "chciałbym" is "I would like" and not "I wanted". Then you have the imperfective "czyścić" which sounds as if you wanted to do it regularly, and not right now. So it kind of seems like you are applying for a job as a cleaning person. A perfective counterpart showing that you want to clean this place so it will actually be clean as a result is "wyczyścić". And still sound a bit strange with "tutaj", better with some specific thing that you'd like to wyczyścić.
But while "sprzątać"/"posprzątać" are very general, "czyścić"/"wyczyścić" only work in some contexts. They're good in the kitchen and in the bathroom, they're generally for removing some spots, some dirt. There are a lot of verbs for different aspects of cleaning and it's hard to explain them all unless on specific examples.