The problem, says a market research guy quoted in this week's Ad Age, is that it's not really Mexican food. What a surprise, right? The Irvine-based chain - and a unit of Yum Brands - is considering adding carnitas to the menu and doing more Spanish-language advertising. Still, it doesn't sound like they're quite getting it. "Food looks like food whether you're Spanish-dominant or Anglo-Saxon," said Debbie Myers, the chain's vice president for media services. Well, not exactly. Says ad executive Carl Kravetz, who handles El Pollo Loco: "If they say they deliver good Mexican food to [Hispanics] they won't be believed. If they say they have good, filling, cheap American food, they may have a chance."