I'm curious what the "rules" are for italicizing foreign words, from an agent/editor perspective. According to my research, the Chicago Manual of Style says you only have to italicize the first occurrence, but I've seen it done differently in a book (Gates of Fire by Steven Pressfield): every occurrence is italicized.
What has been your experience?
Every publishing house has its own style guide.
You'll see it when you turn in your final edited ms, or when you get copy edits to review.
Thus a book published by Snooty Tooty and Cootie may have one way of italicizing foreign words like knickers and catsup, whereas a book published by Hoi Polloi and Cousin Roy may have another.
When you're querying it doesn't matter.
My preference is you not italicize foreign words as long as I can figure out what the word means from context or a quick trip to the google machine.
And who's to say what's foreign?
Hijab may be a new word for some, but it's an item in daily use for someone else.
Same with mami, which I've seen publishers turn into mommy (with great hilarity from me, but NOT from the author).
Some of us think oven is a strange and exotic word, but I am reliably informed that most people not only know it but use one. Who knew?