I'm not sure why anyone wouldn't just make their own guacamole, but if you need a reason to stop using the store-bought goo that passes for the real thing, here's one. Guacamole sold in the past week at Trader Joe's or Whole Foods here may be contaminated with listeria, which you definitely don't want to mess with. Details are in the Tucson Citizen, via AP and Sean at blogging.la.