How long should I keep a dead orchid?

Bit off topic I know but the one plant I cannot abide is that thing with red leaves that comes out at Christmas. I hate the doggone things and always get at least 2 which, despite my treating them very badly, last...and last....and last.

Not clear what OP means by dead? Are the leaves brown and shrivelled? Or is she just referring to the flower stalk.
If leaves all dead, definitely chuck in bin! They are not bulbs/corms. If it has 3 or more healthy leaves then worth a bit of love if you have the space.
A new one costs a princely £6 in my local garden centre - price of a supermarket bouquet and lasts for months. I've got 3 on kitchen windowsills - a good position as it is shady and gets very little direct sunlight.

Phizz The poinsettias. I don't like them either. They need an awful lot of nurturing to get them flowering at Christmas. I once visited a nursery where they showed how they do it. They had automatic shutters to control the light so they flower just when they want them to. They basically need something like 12hrs light and 12 hrs dark and closely monitored temperatures

I don't like throwing any plant away if it stands half a chance of flowering.

I have great respect for those greenfingered orchid growing Grans who manage to do this.

I read recently that the British are very sentimental about their house planats. they try to keep a struggling plant going for ever and ever... the continentals use them as "cut flowers". When they've finished whatever they were meant to d, they are chicked on the compost heap and a new one purchased. I have to confess that I often do that!

So ... grapefruit, if you can bear it, chuck 'em out! Get another.

Just a point re poinsettias: The red part is neither a leaf nor is it a flower; it is a bract. The flowers are those tiny insignificant things you can see if you look closely

I can't keep them, but I do quite like having some in the house at Christmas. Then they go out because the bracts and leaves all start dropping off due to my tender loving care.
DD can grow them to 6' or more in her garden in the tropics.

I did remember to water my neglected orchids the other day after reading this thread and they look as if they will sprout flower stems again despite being forgotten.