If one is invited to a home where you know with almost complete cetainty that they have never toiveled their keilim, and for whatever reason you cannot avoid going there for se’udos,
1) is their a problem to eat with their dishes?
2) use their electrical appliances such as coffee makers?
3) eat food cooked in keilim that were never toiveled?
1. There is a problem with eating from non-toveled dishes, and you should preferably ask to eat from disposable dishes. If this is impossible (for whatever reason), there is room for leniency in eating from non-toveled dishes. It is more important to ensure toveled or disposable cutlery than dishes.
2. Under the circumstances, you can use electrical applicances.
3. The food is fine to eat.
There is a prohibition, in principle, against using dishes that were not toveled (Rema, Yoreh De’ah 120:8). Authorities discuss the nature of this prohibition (rabbinic or Torah).
This obligation applies specifically to the owner of the dishes. However, somebody who borrows dishes from a Jew also needs to ensure they are toveled, and a guest is possible considered as a sho’el.
However, it is possible that somebody eating as a guest is not considered as “borrowing” the dishes, because it is the owner’s use to have guests in his home (see Shut Beis Avi no. 116).
Rav Shlomo Zalman adds a point in that if the guest has an obligation to take the food out of the dish to place it in another (toveled) dish, he can for the same price place it in his mouth (Tevillas Keilim p. 86). This will apply specifically to dishes and not to cutlery.
Another consideration is the status of porcelain (china) dishes. These dishes might be considered kli cheres (earthenware) and therefore exempt from the obligation of tevillah, though most are stringent to tovel them because of their similarity (today) to glass. Again, this consideration will not apply to cutlery.
Therefore, because of the noted considerations there is room for leniency under extenuating circumstances (though for cutlery one should try to avoid the use of non-toveled metal cutlery).