Next time I'll examine the first one that I remove and make a decision whether or not to continue.
There is no guarantee that the next 7 will look the same as the first one. You will have to remove and inspect all of them if you want to be sure.
A couple of months back I had a misfire in my Mustang. I figured I'd start with the plugs since they were about 4 years old. Every plug looked perfect until I got to the 8th one. It had carbon build-up on it to the point of having bridged the gap between the electrodes. With the 8 new plugs installed the misfire was gone. Now if I had stopped after the first one because it looked good, I would've wasted a lot of time trying to track down the problem elsewhere. The moral is assume nothing and double check everything.