There have been a few, but most of them were originally Inner Sphere civilians who were caught in the Invasion.
But part of my point was when the warriors ignored the lower castes and treated them as not being worth paying attention to, it meant that they would likely speak freely in front of them.
Ahh, gotcha. I thought you meant within the Clans. And in terms of speaking freely, I think you're probably right, Clan depending. That said, I think the Diamond Shark Warriors may have treated their Merchant Caste more carefully with what information they divulged.