The original question simply asked if having the inside of the case clean made a difference in accuracy. What the heck needs to be defined?
Just about impossible to quantify any difference in performance between clean or uncleaned interiors. Keep in mind, barring any cleaning media, etc. being left in the case, the burning of powder at 50,000+ psi does a pretty good job of leveling the playing field on the inside of the case. Lots of folks are into the newer liquid cleaning systems that clean inside and outside but I don't see any advantage to it. Personally, I do not want the inside of my necks cleaned. One of the benefits of fire-forming brass is to get a coating on the inside of the neck to make seating and tension more consistent.
If you prefer pretty cases, cleaned inside and out, I do not believe it will be detrimental to accuracy.