Violence: If he is cruel to animals, children, inanimate objects etc, be very careful. This screams unresolved anger issues and may affect you in the future. If he hits you...at all, for any reason, this is NOT a safe situation. Please, don't stay with someone that abuses you. Emotionally, physically, mentally-they all count as abuse. You deserve to be safe with the one you love.
Crude: Sometimes crudity can be tolerated, but if he is excessively crude and vulgar, keep in mind that if you have a minor issue with it now, it will probably grow in time. A friend of mine once dated a guy that called all women Bitches. In fact, the word woman was foreign to him. Even though she repeatedly told him that she didn't want him to call any woman thus in her presence, it was an ingrown habit that was hard to break on his part. Needless to say, the relationship didn't go any further.
Cheating: Once a cheat...always a cheat. In fact, the first time he cheats on you will probably be the only time that he will exhibit extreme remorse and sorrow. He will grovel, beg, plead, do anything to get back in your good graces. Some people have been able to forgive and move on, but there is no way that I could ever forgive a cheater. If you stay with a cheat, you cheat yourself out of a decent relationship with mutual trust and intimacy. With the high risks of HIV and other STDs out there, do you really want to set yourself up for catching something? Also, bear in mind that if you cheated with him and stole him from another woman, there is always the high chance that he will cheat on you as well. There is no way around this scenario, it's just full of pitfalls.
Dependancy: On drugs, alcohol or smoking. Even small habits can grow into huge addictions given time, loss of discipline and the proper incentive. Also bear in mind that behavior changes acutely whenever there is a chemical in the mix. Sleeping tiger, tread softly.
Attitudes towards Women: If he treats his mother, sister, cousin, neighbor, ex, etc disrespectfully and badly, chances are that he could do the same to you. Any guy who treats his mother badly, no matter what a bitch she is, will get an automatic axe in my book. It's your MOM for goodness sakes!
Laziness: Traditional roles still apply. A man is supposed to be the provider and the protector. Plain and simple. If he doesn't work, and you end up paying most of the bills and living expenses then something is wrong with this picture. Please ladies, let's stop coddling to these lazy ass men. We are not their mothers. Kick them out on the curb and tell them to get a J-O-B.
Bear in mind that women are waaaay more adaptable than men. However, just because we are flexible, doesn't mean that we have to be doormats for every lazy, cheating, lying, no-good slob out there.
As a woman of the feminine race, you have a right to be loved, cherished, protected and provided for by the man of your dreams. A Baaad girl doesn't settle for anything less.