Bad accents IG make me cringe, especially bad German ones since I lived in Germany for ten years, but I don't mind them so much if the character's at least convincing as a native. It's when the extent of a native character's development is just affecting a French/German/Slavic/Whatever accent and swapping a few words (often wrongly used in context, gender or form) without any of the lore or racial traits/attitudes that makes me roll my eyes till I'm dizzy.