As long as the stylus is in good condition I wouldn't be overly concerned.
Many of the profiles mentioned in the article (forum) in your second link are for very "high end" styli, hence not really applicable to your average dj or collector of vinyl, although obviously the points raised are valid. There's so much info on the net it's easy to get bogged down with it all. The fundamentals are condition of the stylus & the turntable set dead level. If the turntable isn't level then any settings applied ie tracking force etc are flawed.
As for grading, it's a very subjective matter as we all know, everyone's hearing is different, & eyesight too! Clearly the materials used in manufacture, (vinyl/styrene,) and their quality, will typically have a greater bearing for the average guy in the street than the choice/type of stylus used. Bearing in mind we are normally talking about the evidence of crackles/pops/surface noise etc when grading rather than frequency response/fidelity. Naturally if someone has graded a used records audio quality on their old Dansette and you get the record home and play it on your Linn Sondek you might feel it plays at a lesser grade than stated....can't imagine this happens much in practice.
Finally, (mono) records graded for audio quality either in the mono setting, or with a cartridge wired for mono, will generally sound worse when listened to in stereo. I've had records where one channel has been wiped out (constant distortion) to the point of being unbearable when played in stereo but much better & listenable when played in mono.
Tiberius's post in It's What's In The Grooves That Count - (Record Stylus) was marked as the answer