Oh, I see.

If you want to go lower than I'm no good at you can say I stink at. Both are very common terms.

That's right, but the way I see it there's a "passing judgement + derogative" component there I'm not sure about.

Soy un negado para el baile = I have two left feet

Once, in another forum, some Brit wonder about their "cultural influence" on Argentina as he was surprised we "used" so many litotes. What he called "litotes" -though sometimes they are- is a built-in feature of the Spanish languages. If a whole subjunctive mood -and no just subjunctive cases- exists in Spanish is because our language finds rich ways to communicate using subdued statements and, in a similar way to Japanese art, giving significance to blur, empty spaces and absences.

I'm not saying this because of linguistic pride but to illustrate why these quests for "the exact phrase". I know for sure English doesn't do this by grammatical means but using a well developed and rich vocabulary.

Besides, I know I come through too aggressive in English when I embrace its simpler grammar but neglect choosing the right word.