On my electrics I can strum away quite happily and be relatively pleased with the results. When I pick up an acoustic my strumming emphasises the thin 'e' string. This happens with down and up strums. The result is a high pitched ringing throughout, giving a harsh and tinny rather then smooth melodic sound. I have tried varying the slope of the pick and thinner picks.- better but not cured. Its obviously a fault with my action but I don't know why it does not show on my electrics.