I dont know about any one else,but my husband used those very words on a few occasions,and really although the description is colorful,it is pretty spot on.
If you think about the carnage radiotherapy causes inside the mouth ,in fact if you ever ask him to open his mouth and take a look inside you will see what causes this feeling.

The radiotherapy burns everything in its path ,cancer and healthy tissue,and the lining of the mouth is very delicate.
Then imagine you have scalded yourself with boiling water and have full thicknes burns on say for instance your arm.what happens next?blisters,then weeping sores,then scabs,then dead skin dropping off then hopefully healthy tissue underneath.
It is the same in your husbands mouth except because it is in the mouth you dont get the scabs because the mouth is so moist and instead you get what is called sloughing ,where the dead skin comes away as a slimy exudate instead,and of course it may get infected with thrush which will make it all seem worse.
Add to this the saliva turning to the consistency of wall paper paste and you have a pretty depressing picture.
I think you will find his description not at all unusual at this stage,but it will get better,its very early days.

Sorry if this is a bit too graphic but i dont know how better to describe it.

love liz