The Cat is full of shit. Really

[DogCalledRudis]

Locked her inside toilet -- litterbox is there. She peed and pooed, and when she got out, she crapped on the floor.

Why did you lock her in? It could be she was stressed, that causes bad toileting habits in cats.

Well stressing and upsetting her is a sure fire way to get her to shit herself regardless of whether she had previously been.

She wouldn't use litter tray otherwise.

What have you tried?

We tried different litters. She preferred one single sort. Otherwise she'd toilet beside it. Then she discovered the roof. We stopped her going, now looks like she's punishing us.

Sometimes I have lock mine in the utility room for half an hour so he'll go, it's that or you have to watch him like a hawk all night.

You have been punished though.

Could you get a Felliway plug in? Maybe she's just a bit uneasy and it could help. Cats don't like being messy, it bothers them, there's usually something amiss if they are crapping all over the place

Locking in a toilet helped my parents cat. But to this one its not enough:(

I would try feliway. And then seek veterinary attention. Maybe she struggled to feel even she needs to go or food isbnt agreeing with her or there's something stressing her that you haven't thought if but an outside person could see.

How old is she? Was she house trained before you got her?
It's really not on to lock her in a room to make her use a tray, that'll cause her a lot of stress and from that possible health problems.
If she likes to toilet outside have you tried putting the tray out there?

Following on from what Mogz says, she may well view the tray as something unpleasant/frightening because she associates it with being locked away. Making her less inclined to use it.

She sounds very stressed and unhappy... not surprising really.. you wouldn't lock a child in the loo til they peformed! You need to take the pressure off, put the tray maybe near the back door, or somewhere secluded that she feels comfy using and be very gentle with her poor girl.

I'm lurking on the cat section because I'm about to get a new kitten (we lost our lovely young cat the other month) and am going post a picture. I'm frankly stunned that your cat went after you locked her in the bathroom. Cats IME don't pee or poo to order if you want that you need a dog! 35 years of cat ownership and ours would never do that. Our cats seems to have a thing about a shut door what ever side they are of it.
I'm unconvinced cats really do punish people! Is it the food? The only time ours have pooed away from their tray is when they've upset stomachs, are eating food that doesn't really agree with them or as others have said are stressed.

Looks like the trick worked. Now she understands what is expected of her.
(Knocks on wood)