Welcome to Pet Talk, Bunny.

As far as a cat actually eating plastic bags, it is like the others have said, I'd check Ripley's diet, to make sure that she is getting all the nutrients that she needs. It could be that she likes the "crakly" sound from them. Personally, I feed my furkids with dry food left out all day, so they can eat whenever they are hungry. Also, in the mornings after I get up, I feed them dry with some canned mixed in. This way I am sure that each one gets fed properly. Subsequently, I have no problems with any of them eating things they are not supposed to -even plastic grocery bags. I have 2 cats that have to be fed separate from the others, otherwise, Amy will not eat anything and Tiger will barf up what ever meal the others have eaten. Also, for a deterrent, you could spray any plastic bags you have stored away with cologne -cats hate it. I hope this helps.

...........wayne