I should clarify. It doesn't necessarily affect the function. It makes things a bit more complicated since you can not judge the knife completely on the manufacturer. The skill of the buffer is a factor. Did he do a good job? Did he ruin the heat treat? Did he apply too much lateral pressure? Was it necessary to thin out the blades a lot to get past any pitting? Etc. If the knife was used previously that is also a factor. Did the prior owner use the blades as pry tools? How is the walk and talk? Etc. But it is correct that a buffed knife can be a good user. A parts knife and a fake can be a good user also. But you just can't assume that they are representative of a factory fresh knife from Case.