I'm a management employee at a fairly large company. If your employer ever gives you an “Engagement Survey” to fill out, anonymously or not, think twice about filling it out. This is especially true if you and your co-workers are thinking about organizing. Companies frequently use this data to identify and kill potential unionizing hotspots or to root out particularly “problematic” individuals or groups of employees.
Always assume that the company you're working for is working against you because they are.