My poor cauliflowers

My only successful cauli's went like this - I think it's to do with too much rain in the late stages - it can cause a rot I think.
It's recommended to bend some of the big leaves over the white curds so the rain doesn't get to the curds.

Shame though - it's such an effort to grow them

I'd have thought you'd be able to chop off the manky bits and save the rest (whether frozen or cooked immediately).

Just my thought too, however bad it looks, it might just be slug damage. In this case, as Yorkie says.

For future, do more in the slug control department, that's where soft rot and such like can set in.

I'd have thought you'd be able to chop off the manky bits and save the rest (whether frozen or cooked immediately).

Doesn't look very appealing though does it?
When mine looked like that, it does go right down into the curds and smells and you don't even want to attempt eating it.
Calabrese broccolli can get the same thing with their curds as well - the last couple of mine didn't look edible - I should have covered the curd with a leaf to protect it.  It was however the most successful year for calabrese for me ever though, so there is hope for caulis in the future - provided they don't get eaten by slugs as all mine have this year