The people I work with (microbiologists) are obsessed with food hygiene. So, every time there's an expose on poor food practices they watch it and come back in the next day with a full run down. So they saw the program that said the salads were washed in bleached. If you wash them off you'll be fine, but the main problem is that these salads are sold as 'ready to eat'. While a human tum can probably cope with the residual bleach left on the leaves, it isn't something that I personally want to risk with my bunnies. If you give the salads a clean before you feed them then there shouldn't be any problem, but then if you have to wash them yourself why are you paying the extra money to have someone else wash it and put it in a bag for you?
I don't buy the prepared stuff anyway. I find that they prefer cheap veggies to more expensive salads and fruit, which suits me just fine.
Oh, and it is just the stuff that's sold as 'ready to eat' that's been washed in this way. I don't know who the main culprits are as I didn't see the program myself.