Question #1:
“My rav discreetly told me to avoid using a particular hechsher which I see is very popular. I am curious why this should be so. I know that there are negligent hechsherim out there, but don’t all reliable hechsherim follow the same Shulchan Aruch?”
Question #2:
“Some of my friends use specific hechsherim, and do not use others. Is there something halachic behind these distinctions, or is this simply politics?”

  “I know that I only eat from certain hechsherim. However, my sister-in-law, who is a very frum person, was told by her Rav that she can use a certain hechsher that I was told not to use. Don’t all the rabbonim follow the same Shulchan Aruch?” “I have been told that it isn’t possible [...]