The worst example of the "casserole made with condensed soup" was at my very English SiL's house in the UK.
It was made of:
cooked, chopped chicken
a tin of water chestnuts
a tin of condensed chicken soup
chopped celery & onion
mayonnaise...
All mixed together and baked.
The absolute depths of revulsion were reached with the "crunchy topping": bad enough that it was supposed to consist of cornflakes and grated cheese mixed together and sprinkled over; SiL had run out of cornflakes so put bran flakes on instead.
It was like textured lumps in wallpaper paste topped with cheesy cardboard.
Ick.