"나는 맛없는 케이크를 팔아요."

Translation: I sell a tasteless cake.

[JanicekSuh]

So brutally honest about how horrible they bake :/ At least say something like "I sell delicious cake" so it sounds convincing haha. I understand that this is in negative form because it's spelled differently.

[wintertriangles]

It's the baker from sweeney todd

[musicamuse]

who's duolingo shading today

[wackadoo1]

Must be a gluten free cardboard cake

[dexikiix]

Why does the topic/subject particle get used on tasteless?

[Ellie850831]

It's actually a verbal modifier in this case. It turns a verb stem into an adjective

[UltimetaSy]

This is a tricky one.

There are 2 types of ㄴ suffix:
1. 은/는 topic particle just like you said, 은 after consonant, 는 after vowel.

1. ㄴ/는 adjective modifier. ㄴ after vowel and word with ending ㄹ, 는 after consonant. 길-긴, 있는, 없는