Its amazing how people will go back to someone who will sell them crap
Depends on the dealer. Obviously you always want to be polite about it.
But if I hardly know the dealer, I won't say shit and I just move on to the next one.
If it is somebody that I have been dealing with for a while and consistently gets high quality product, and I end up with shit, obviously I will say something. I've never run into any problems doing this.