I have read somewhere that the fraud AND DWP error rate for disability benefits is either 5% or 0.5%, can't recall now, which makes this post a little useless! but demonstrates that against other benefit fraud AND error is very very very low.
And re: good days, bad days - I'm one of those. Last week for example, I was able to go outside nearly every day. The week before that I got out once. Over the summer I couldn't do more than literally drag myself, be dragged to the loo and back to bed for 3 weeks solid. the rest of the time I hover somewhere in between. Some days I can get about easily outside, but I still need to be dressed and washed, have all the housework done for me etc - yet nobody sees that part.
If I were investigated on a good week it gives an unfair impression of my overall abilities.
This week I've not been out so far, although it is only Tuesday of course, but with the ice down even if I felt able, I am housebound till it clears.
I really hope anybody reading this thread will think twice before judging people in future. you can never know the whole story.