I'd have to say:
1) Other - just because of the massive, wide ranging endless possibilities of "turn offs" that go in this category. Arrogant personalities, ignorance for me is... difficult to take in other people, someone with no sense of humour will never be able to interact with me, too much ego is ugly, etc etc
2) Drugs - i say this because I've been down that road. made some bad choices, although i dont believe in regrets because ive learned so much, but im glad im not there anymore. I know what kind of effect they can have on you and your life, and that they change your personality. When i am around people who do certain drugs, i have to remove myself because it reminds me of how i was, and i really didnt like who i was back then. so, this is just a no-go, i'm afraid. i have friends with problems, still... but i refuse to be around them if they are under the influence.
3) Smoking, i guess. im a smoker... edging towards the "quitting stage" but refuse to use that word until i can commit to its meaning. but i think i would only have a problem with a smoker if i was no longer one, which will hopefully be so in the near future. but if i was still smoking, i couldnt give a rats ass.
4) Overweight - Just because 20lbs overweight means so little to me, i suppose. i'd much rather someone a little overweight than underweight, at least there's sumthin to hold on to.
Oh, and as an aside: having said all of the above, I'm sure it's partially bullshit, because i have no doubt whatsoever that there exceptions to each and every above-mentioned rules.
I try not to write people off according to their flaws, because i have so many myself, and wouldnt want someone doing that to me. I think often the little flaws and imperfections are the greatest part of someone's character.
Everyone, with no exceptions, is flawed and imperfect. And my god, isn't that just great? Like, honestly. If no one had any flaws, everyone would be beyond boring, and i think i would hate everyone, and there would really be no purpose to humanity at all.
Flaws have a bad rep. I think they're great, and the best people and most amazing friends i have in my life, are deeply flawed, and have gone through many bad choices, wrong turns, indulged in their "flaws" - but how one get's through such things, overcomes them, deals with them, how they indulge in them, etc... these are all factors that lead to forming fascinating and strong characters.
flaws in people are like bad choices in life... they come part-in-parcel, but they're up to you on how to navigate around them or confront them - and how you do that, determines where you end up on the other side.
Anywho, don't indulge... moderation is the key. Something i struggle with daily, one of my greatest "flaws" is that i have a highly indulgent (see: addictive) personality. but flaws go both ways. yes, i ended up going the drug route, am still on the smoking route, etc... but then, there is the good side. when i look into an issue, i indulge in its information, and in reading, and have developed an addiction to information about as much as i can find out about, which has led me to where i currently am in life, somewhere i am, for the first time in a long time, happy to be.
so... flaws.... have a bad rep.
just like everything, it's balance.