@optimize , Like anything in life there is a range of tolerance usually decreased by monetary issues. A cartridge manufacturer orders so many of one particular cantilever-stylus assembly. Within that order there is a range of accuracy. The manufacturer selects the best units for his expensive units and religates the not so hot ones to lesser models. Perhaps the real bad ones are returned for credit. All the poorly mounted styluses I have observed have been on cartridges under $1000.00. I have three $10,000.00 plus cartridges and all are perfect. I also have a $3000.00 Soundsmith cartridge that is perfect.
Zenith error is a more critical issue for fine line contact styluses. If the error is enough for me to see it under low power I would return the cartridge as defective. Twisting the cartridge to correct the error now puts the coils out of alignment. Bending the cantilever is out of the question, try it if you do not believe me.
Most people do not look at their cartridges under good magnification. Good magnification is expensive. If you are an audiophile spending over $500 on a cartridge it is a good idea to have the stylus alignment examined by someone who knows what they are looking at like J.R. above. Do it early while the cartridge is brand new and under warranty. Do not assume because your cartridge comes from a reputable company that it is OK. The absolute worse cartridge I ever examined was from Audio Technica. Nobodies QC is perfect.