I wouldn't go as far as to say it's a turn off, more like characters with such attributes generally do not appeal to me.
1) The cutesy type. Many otome games have at least one character that fits into this stereotype -- they tend to be shorter compared to the other LIs, have larger puppy-esque eyes, and an innocent, almost childlike/childish aura about them. Even worse (for me) if they're overly cheerful, hyper, loud and boisterous. And even more minus points if they're wearing, like, frilly shorts, constantly winking, sticking their tongues out, or making peace signs, HAHAHA. I like characters who are/look/act/dress more mature.
2) This probably sounds funny given that I've just mentioned above that I like mature/mature-looking characters, but I also don't like facial hair. I like my LIs clean-shaven.
3) Characters that have overly patriarchal views, or say things that suggest they do. Example: "Ahhh, I can't imagine how happy I'd be to come home to you every night, eating the food you lovingly prepared for me." I get that it's supposed to be romantic, and some people DO find it romantic, but I don't quite appreciate being indirectly told that I should become a housewife after we get hitched, haha. I know most otome content comes from Japanese/Asian creators, and being Asian myself, I'm aware that sometimes it's inevitable/unavoidable considering how gender roles are still rather clearly defined in Asian societies. But yeah, sometimes it kills the mood a bit to have a LI say something along those lines.
4) It's usually the MC who gets written in such a way, but basically one who is overly pure, trusting, and airheaded. Even worse if she's a klutz on top of all that, HAHA. I don't expect all MCs to be depicted as highly capable over-achievers with an IQ of 180, but the REALLY dumb and naive ones annoy me too much. I'm the type to self-insert, and such MCs make it VERY hard for me to do so.
