Those are the three things that YBS1 says you do not compromise on.
Mayonnaise, definitely. Though once I began to bring Gefen Lite mayo into our home, our standards relaxed somewhat. It definitely tastes better than Hellman's Lite mayonnaise. And we are mayonnaise experts around here. It is as essential to a Shabbos meal as challa and wine.
Ketchup, sad to say, seems to be only be tasty if it is Heinz. Although I am not a picky eater, there really is a difference in the taste. What actually prompted this was YBS1's observation that I bought a non-jewish brand of chummus *(which the brand calls "hommos", already an indication of not getting it right), and a jewish company's ketchup. He thought this was problematic. He is prone to grand sweeping all encompassing statements, as he said,
"What do these people know about making chummus? And what does Lieber's know about making ketchup?! and what about these off brands of mayonnaise ??"
and then followed his most profound statement of all,
"there are just some things in life you do NOT compromise on! Mayonnaise! Ketchup! and Yiddishkeit!"