Jorge Lopez has a television show that hasn't been cancelled as of yet. Think about that for a second. Have you watched more than 5 consecutive mintutes of the Jorge Lopez show on purpose? Guy doesn't have a funny bone in his body. It's not his fault, its genetic, he's of Latin blood.
Carlos Mencia had a television show. Was Carlos funny? No, no he wasn't. I mean this guy is so un-funny that he actually stole about 20 minutes of Jorge Lopez's act. But again, it just wasn't his fault. Mexican and Latino culture just don't play well on the American comedy scene.
Blacks have their oppressed history, hatred and distrust of white people to make light of. Whites fall back on white trash humor, self depreciation, and wealthy guilt. Jews? They're just naturally hysterical. Gay comedians have been barrels of laughs in recent years, apparently there is a huge market for Brokeback Mountain jokes, hell I've even seen a few funny Indians, but never a Latino.
Latin culture just doesn't play well to an American audience, there just isn't that much that we relate to or care to understand going on there. Big families, loud fiestas, funny mustache's, and multiple variations of tortilla/beef/cheese/and salsa foods. Love your tacos, hate your parades and loud voices, ambivalent to your "comedy." Sorry, it just doesn't work like other cultural comedy.