Take an expression like déjà vu. This is a French term which is frequently seen in English. In fact, it is included in English dictionaries. But it is often seen in English in a variety of forms:
Now, one would probably not consider using frisson or soupçon, both proper unanglicized French words [uh-oh, see edit], without italics to indicate that they were foreign words. But once anglicized, do the words require non-English diacritical marks? Or, if such are used, does that push the word back into foreign status, so that italics are again required?
There's probably a continuum in operation here, during which a word goes from foreign with foreign markings to English with only English markings (or lack thereof). What I want to know is how one can tell where to draw the line. Does anybody have any useful information about this? Guidelines? Or is it on a case-by-case basis?
Honestly, I feel affected writing à la carte when every damn diner you walk into has an "a la carte" (or "ala carte" or "a la cart") category on the menu.
Edit: For example, see the Free Online Dictionary's schizophrenic listing for soupçon:
Soup`con´ n. 1. A suspicion; a suggestion; hence, a very small portion; a taste; as, coffee with a soupçon of brandy; a soupçon of coquetry.
and then in the Thesaurus part:
soupcon - a slight but appreciable amount; "this dish could use a touch of garlic"
So if dictionary entries can't even remain consistent within the same definition, what chance does a mere mortal have?