Hooters has actually lost based on gender discrimination, and as part of the settlement, they had to create support jobs that men could fill. They could still continue to hire only women as wait staff, though.
Interestingly, you can legally discriminate based on attractiveness, as long as you're not basing your judgement on any of the protected bases: gender, disability, race, etc.
Being ugly is not protected. You can legally be passed over for a job if you don't look good to the employer. Not if you're fat, though. You're not allowed to discriminate due to obesity, because it's considered a protected disability under the law.
I guess having a penis is a protected disability, too.
