Q:

Should sweet potatoes be peeled when preparing them? 

I want to make a sweet potato dish -- maybe candied yams.   Should I peel the sweet potatoes before cooking or are these recipes intending for me to keep the skin on?   None say to peel the potato first. 

A:

Candied Yams, I would peel first. 
However, for mashes and other similar soft dishes, I find it best to bake them until soft and then remove the peels when cool. 

A:

I like to maintain the shape, texture and nutrition of my sweet potatoes, so I try to avoid peeling.   Sweet potatoes have a naturally thin skin so most recipes can survive.   I usually cut off the two thin tips (tend to be drier and harder) but then scrub the potatoes. 
Next step depends on the recipe.   If you are going for mashed sweet potatoes and you are fine with the concept of "dirty mashed potatoes" where you leave some of the skin on, this will work great for a rough mash with great texture.   If you are of the mind that mashed sweet potatoes have to be smooth and fluffy, then you are going to have to peel. 
For candied sweet potatoes, I cut them so they are circles about an inch or so thick and lay them out on the bottom of a buttered baking dish.   Sprinkle some butter, brown sugar, crushed pecans and/or coconut on top and bake.   The skins help the circles stay together and, again, are so thin that they don't get in the way. 

A:

It comes down to personal preference.  Sweet potato skins are a bit tougher than regular potato skins.  I don't find them very appetizing.  In every candied yam recipe I've made, eaten, or seen the sweet potatoes have always been peeled. 
Also keep your guests preferences in mind.  You're much more likely to please everyone with the peeled potatoes than with peels on.