This is just nasty and there is no excuse for these practices. Heck, if I was a crew member I would probably file a lawsuit for having to sleep with blue cheese. I love it but the smell would be terrible.
I don't believe this is standard to the industry but I see it as a sign that Silversea has real problems and not just in the galley. If this is being allowed in the galley what else is happening in other departments?