That moment when you get it wrong because you accidentally pressed enter trying to type out the answer lol!
How many of us have groaned when a stray digit has somehow sent a well thought out answer/ something we happily knew/ a moment of inspiration into cyber oblivion. Just occasionally, Duo seems to suspect there has been a mishap. More often than not, the ding of failure peels! C'est la vie, I suppose but less polite expressions must ring out amongst us :)
Both are acceptable. In English, we would more commonly say "cleaning," but the French form used is actually the infinitive, for which the English translation is "to clean," which is completely acceptable in English. Using "to clean" is perhaps more literally correct, while using "cleaning" is perhaps more contextually correct, given the way that verb forms are used in English.
Propre is an adjective, meaning clean, while nettoyer is a verb meaning to clean :)
Because that would be "déteste", it's a stronger word than just "n'aime pas".