All in your mind. These are digital cables. The 1s and 0s goes in one side and out the other. If the same signal goes in that comes out, the cable is doing its job. If not, you'll see sparkles and lines and obvious problems in your pictures because the 1s and 0s no longer "make sense" to the TV. The cable will not improve or decrease sharpness, screen refresh rates, color, tint, brightness, contrast or the price of oil.
Basically if the cables are working, you don't need to change them. If you do start to see artifacts (not changes in picture quality) then it's time to change cables. If you do change cables and you have a choice then use certified high speed cables, such as the ones you can get from monoprice. The price difference is now so small that it makes sense to use high speed when ordering new cables.
What higher gauge cables provide are longer lengths (much greater than 25') without causing bit errors, everything else being equal.