I'm questioning residence listed in the Civil War Profile. Anyone who does this long enough eventually begins to ask, where did they get this information? I find no source for residence in the soldier's service file, so I've begun to question all their residence information.

It's not reasonable to state that all soldiers of any regiment came from one county. By the same coin, we shouldn't assume that a because soldier belonged to a regiment, he must have come from a particular county. You can do that at the company level for most early war volunteers, but even then you should verify from the census or another period source.