Anyone have a case study or report?

Has anyone seen a case study or report proving that customers will choose a clean facility, business, resturaunt, gas station, etc. over a dirty one?

I think it would be cool to have something like this as marketing material instead of the customer taking our word for it. It would be really cool to show a documented study with real life statistics of a business being more productive after it was regularly cleaned.

I imagine they have been done, that would be a great selling tool.

Let's make one...