I can't say for sure that your place of employment is like mine, but I know that similar perceptions are held by many were I work. These folks tell corporate that it is a waste of time to separate since it all gets combined. Corporate repeatedly tells them that it actually is getting recycled, the company is saving money by not having to pay trash hauling fees, and they give figures to prove it. The argument never gets resolved. But through my own observations I've noticed the following after being bothered by this myself.
1) Deposit bottles/cans - if placed in the more limited number of containers around the company they are picked up by special needs groups. Special needs folks do the pick-up giving them a job and they get the deposit money for the group's programs.
2) Paper recycling - the bins that the cleaning staff wheel around all look the same. I've realized that the staff often have 2 separate bins with them though you only may see one out your door when they stop by.
So while there may be some instances of the waste stream being combined, I'm pretty convinced at this point that the majority of it is properly recycled.
My advice if you think your employer is putting on a big charade just for looks is to ask the question - How much is the company saving on trash hauling by recycling? Ask the person or group in charge of facilities if the cleaners are actually separating. It may be that the cleaners are supposed to separate but don't because they are lazy. Or they do and you just can't tell. Ask questions, make a little noise and you can help get the situation resolved. Not everyone can be convinced, but if the recycling program is a farce you can make sure it becomes a real one.