I eat lettuce right out of the bag. Since people know I teach and write about food safety, quite often they ask me about re-washing pre-washed bagged lettuce. I don’t and neither does Dr. Ben Chapman, the NCSU state specialist in food safety.
Chapman said in a recent post to barfblog.com, a daily food safety blog he writes with Dr. Doug Powell, there’s really not much you can do, safety-wise, to bagged lettuce once it’s in your home. If there’s pathogenic E. coli, Listeria or Salmonella there (or others) you’re stuck with it.