They stopped the commercials a long time ago. I think the last one was aired back in 2000-ish. There was a nasty lawsuit regarding the ads. Not only that, but the Latinos/as of America found the ads "exceedingly stereotypical and offensive". I'm hispanic, and think they were freaking awesome. Some people just like to bitch about everything, and ruin good things for the rest of us.
Taco Bell lost a lot of money in the lawsuit though. Apparently these 2 guys pitched the idea to them years before the ads started. TB said "no no no". Few years later, bam! we got a talking chihuahua! Guys came back and sued the nacho cheese out of them. They won.