If you took more than 10 prep tests and still score under 140, there is a problem. Statistically, people who do poor on LSAT have big problem passing the bar.
I read it somewhere that most blacks don't pass the bar on their first try. This is due to affirmative action where low LSAT blacks are being admitted. It doesn't matter what the color of your skin is, if you do poorly on the LSAT, chance are you will have problem passing the bar exam. Keep in mind that if you fail the bar exam twice, that's a whole year of time passed, since the bar is offered twice a year.