Plugin for demo site, show comment form, disable actual submission?

Hello!

I was wondering if a plugin exists (and I may be searching the wrong terms) that won’t hide my comment form or status, but simply not accept new comments. They’ll be “submitted”, but never hit my database.

I have many demo sites set up and they get a ton of spam, I don’t actually allow any real comments to be approved so I’d like them all to simply be denied, yet show the demo comments and comment form for demonstration purposes.

Any suggestions? Thanks!