Cleaner due to their thicker skins, yes,
but you still gotta wash them before cutting or eating... This is my compilation of several lists of the 'cleaner' produce I call the "Clean Eighteen"
In my amateur-foodie opinion, with thicker skins these conventionally-grown fruits + veggies are okay to buy because you're cutting off most of their outer skins anyway; so it's fine to spend your hard-earned money elsewhere in your grocery budget instead of forking it over for the more expensive organic version.
sweet peas (frozen)
citrus (like lemons, limes, oranges, grapefruits)
Or buy all organic if you feel more comfortable, as always, it's completely up to you.
As a tip: Use a soft bristle fruit + veggie brush like this one by Oxo scrubbing under some clean running water which is great to help wash off any dirt or grimies from your produce before cutting or consuming. I personally have one of these little brushes + love it.
(No, Oxo has not provided me with any free product or compensation to say so...just passing along some useful product info.)