It's funny to see how differently people react to the same foods. I'd personally not find Pringles to be gag-worthy, and as for curry, they of course come in many different varieties, some quite nice, some not so much.I'd rather someone brought a delicious aromatic curry on the train, than those disgusting smelling cream cheese flavoured pringles that make me want to gag.
I think what makes some smells even more intolerable is in the confined space of a train, that you can't easily escape from.