Clean old oven before they take it away?

[ThoughtExperiment]

We have recently moved into a new house and are having a new oven delivered soon. The existing oven is quite mucky - it wasn't great when we moved in and I haven't been bothered to clean it much since we've been here as I knew we were getting a new one soon so it's in a bit of a state - not disastrous but definitely not clean! It would require a good bit of scrubbing to clean it up, not just a wipe down....

John Lewis are delivering the new oven and will take the old one (and hob) away for free. My question is: is it a serious breach of etiquette if I don't clean the old oven before they take it away? Would they expect it to have been cleaned? If I can get away with it I won't bother but wonder what you would all do?

Dreadfully dull question I know, but humour me...

Are you mad?

That is all. The whole point of moving house is to get out of cleaning the oven by buying a new one.

This is something my grandma does. Tidying the house before the cleaner gets here, so she doesn't look as messy!

Madness I tell you! Say goodbye to that oven, muck and all!

Oh thank you for the responses! I will leave it then! In fact am going to cook a really messy, spitty, roast beef in it tonight to bid it a fond farewell!

And contrary to popular mythology, there isn't a "John Lewis Panel of Judginess" - chaired probably by the ghost of Mrs John Lewis, who will run a damp finger along your discarded oven, tut, and have you barred from all John Lewis & Waitrose establishments for ever.

Go for it thought. You are free. Free I tell you.