The common factor in these suggestions: securing support from the ones who have final say over how the space is used.
(There are less-professional deterrents — missing light bulb, "biohazard" sign on door, opened sardine tin in trash can — but it would be irresponsible of me even to suggest them.)
As for pleasantries, you can always lob the first "Good morning." When outside teams are brought in to "streamline" things, being on their good side isn't a bad idea.
Thanks to Sharon Snyder, of the Ober Kaler law firm.
Karla L. Miller writes an advice column on navigating the modern workplace. Each week she will answer one or two questions from readers. Miller has written for and edited tax publications for 16 years, most recently for the accounting firm KPMG's Washington National Tax office.