Personally I haven't found any that liked a dirty bore. Most all like shooting form a FOULED bore, but not a dirty one. But every barrel is different and don't doubt that some may like it dirty...

As for your scope, your are correct, many can and do get "sticky" and don't "Jar" loose until a couple shots or they are adjusted far enough away from there initial settings. As a rule this does not happen with higher quality scopes. At least not nearly as much. Something I have done for years and years is to gently 'tap" with the back of the screw driver on the turret adj screw after any and all adjustments. Also going a couple clicks past, then returning to where you really want it set can help.
Good luck and good shooting,

CW